NCERT Exemplar Class 8 Maths Chapter 7 Algebraic Expressions, Identities and Factorisation

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NCERT Exemplar Class 8 Maths Chapter 7 Algebraic Expressions, Identities and Factorisations are part of NCERT Exemplar Class 8 Maths. Here we have given NCERT Exemplar Class 8 Maths Chapter 7 Algebraic Expressions, Identities and Factorisation.

NCERT  Exemplar Class 8 Maths Chapter 7 Algebraic Expressions, Identities and Factorisation

Multiple Choice Questions
Question. 1 The product of a monomial and a binomial is a
(a) monomial (b) binomial
(c) trinomial (d) None of these
Solution. (b) Monomial consists of only single term and binomial contains two terms. So, the multiplication of a binomial by a monomial will always produce a binomial, whose first term is the product of monomial and the binomial’s first term and second term is the product of monomial and the binomial’s second term.

Question. 2 In a polynomial, the exponents of the variables are always (a)’integers (b) positive integers (c) non-negative integers (d) non-positive integers
Solution. (c) In a polynomial, the exponents of the variables are either positive integers or 0. Constant term C can be written as C x°. We do not consider the expressions as a polynomial which consist of the variables having negative/fractional exponent.

Question. 3 Which of the following is correct?
(a) ({{left( a-b right)}^{2}}={{a}^{2}}+2ab-{{b}^{2}}) (b) ({{left( a-b right)}^{2}}={{a}^{2}}-2ab+{{b}^{2}})
(c) ({{left( a-b right)}^{2}}={{a}^{2}}-{{b}^{2}}) (d) ({{left( a+b right)}^{2}}={{a}^{2}}+2ab-{{b}^{2}})
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-1

Question. 4 The sum of -7pq and 2pq is
(a) -9pq   (b) 9pq
(c) 5pq   (d) -5pq
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-2

Question. 5 If we subtract (-3{ x }^{ 2 }{ y }^{ 2 }) from ({ x }^{ 2 }{ y }^{ 2 }), then we get
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-3
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-4

Question. 6 Like term as (4{ m }^{ 3 }{ n }^{ 2 }) is
(a)(4{ m }^{ 2 }{ n }^{ 2 }) (b) (-6{ m }^{ 3 }{ n }^{ 2 })
(c) (6p{ m }^{ 3 }{ n }^{ 2 }) (d) (4{ m }^{ 3 }{ n })
Solution. (b) We know that, the like terms contain the same literal factor. So, the like term as (4{ m }^{ 3 }{ n }^{ 2 }) , is (-6{ m }^{ 3 }{ n }^{ 2 }), as it contains the same literal factor ({ m }^{ 3 }{ n }^{ 2 }).

Question. 7 Which of the following is a binomial?
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-5
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-6

Question. 8 Sum of a – b + ab, b + c – bc and c – a – ac is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-7
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-8

Question. 9 Product of the monomials 4p, -7({ q }^{ 3 }), -7pq is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-9
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-10

Question. 10 Area of a rectangle with length 4ab and breadth 6({ b }^{ 2 }) is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-11
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-12

Question. 11 Volume of a rectangular box (cuboid) with length = 2ab, breadth = 3ac and height = 2ac is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-13
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-14

Question. 12 Product of 6({ a }^{ 2 }) -7b + 5ab and 2ab is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-15
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-16

Question. 13 Square of 3x – 4y is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-17
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-18

Question. 14 Which of the following are like terms?
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-19
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-20

Question. 15 Coefficient of y in the term of ({ -y }^{ 3 }) is
(a)-1 (b)-3 (c)({ -1 }^{ 3 }) (d)({ 1 }^{ 3 })
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-21

Question. 16 ({ a }^{ 2 }-{ b }^{ 2 }) is equal to
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-22
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-23

Question. 17 Common factor Of 17abc, 34a({ b }^{ 2 }), 51({ a }^{ 2 })b is
(a)17abc (b)17ab (c)17ac (d)17({ a }^{ 2 })({ b }^{ 2 })c
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-24

Question. 18 Square of 9x – 7xy is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-25
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-26

Question. 19 Factorised form of 23xy – 46x + 54y -108 is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-27
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-28

Question. 20 Factorised form of ({ r }^{ 2 })-10r + 21 is
(a)(r-1)(r-4) (b)(r-7)(r-3) (c)(r-7)(r+3) (d)(r+7)(r+3)
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-29

Question. 21 Factorised form of ({ p }^{ 2 }) – 17p – 38 is
(a) (p -19)(p + 2) (b) (p -19) (p – 2) (c) (p +19) (p + 2) (d) (p + 19) (p – 2)
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-33

Question. 22 On dividing 57 ({ p }^{ 2 }) qr by 114pq, we get
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-30
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-31

Question. 23 On dividing p(4({ p }^{ 2 }) – 16) by 4p (p – 2), we get
(a) 2p + 4 (b) 2p – 4 (c) p + 2 (d) p – 2
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-32

Question. 24 The common factor of 3ab and 2cd is
(a) 1 (b) -1 (c) a (d) c
Solution. (a) We have, monomials 3ab and 2cd Now, 3ab = 3xaxb 2cd =2 x c x d
Observing the monomials, we see that, there is no common factor (neither numerical nor literal) between them except 1.

Question. 25 An irreducible factor of24({ x }^{ 2 })({ y }^{ 2 }) is
(a)({ a }^{ 2 }) (b)({ y }^{ 2 }) (c)x (d)24x
Solution. (c) A factor is said to be irreducible, if it cannot be factorised further.
We have, 24({ x }^{ 2 })({ y }^{ 2 }) =2 x 2 x 2 x 3 x x x x x y x y Hence, an irreducible factor of 24({ x }^{ 2 })({ y }^{ 2 }) is x.

Question. 26 Number of factors of ({{left( a+b right)}^{2}}) is
(a) 4 (b) 3 (c) 2 (d) 1
Solution. (c) We can write ({{left( a+b right)}^{2}}) as, (a + b) (a + b) and this cannot be factorised further.
Hence, number of factors of ({{left( a+b right)}^{2}}) is 2.

Question. 27 The factorised form of 3x – 24 is
(a) 3x x 24 (b)3 (x – 8) (c)24(x – 3) (d)3(x-12)
Solution. (b) We have,
3x – 24 = 3 x x – 3 x 8= 3 (x – 8) [taking 3 as common]

Question. 28 The factors of ({ x }^{ 2 }) – 4 are
(a) (x – 2), (x – 2) (b) (x + 2), (x – 2)
(c) (x + 2), (x + 2) (d) (x – 4), (x – 4)
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-1

Question. 29 The value of ((-27{ x }^{ 2 }y)div (-9xy)) is
(a)3xy (b)-3xy (c)-3x (d)3x
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-2

Question. 30 The value of ((2{ x }^{ 2 }+4)div (2)) is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-3
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-4

Question. 31 The value of ((3{ x }^{ 3 }+9{ x }^{ 2 }+27x)div 3x) is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-5
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-6

Question. 32 The value of ({{left( a+b right)}^{2}}+{{(a-b)}^{2}}) is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-7
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-8

Question. 33 The value of ({{left( a+b right)}^{2}}-{{(a-b)}^{2}}) is
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-9
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-10

Fill in the Blanks
In questions 34 to 58, fill in the blanks to make the statements true.
Question. 34 The product of two terms with like signs is a term.
Solution. Positive
If both the like terms are either positive or negative, then the resultant term will always be positive.

Question. 35 The product of two terms with unlike signs is a term.
Solution. Negative
As the product of a positive term and a negative term is always negative.

Question. 36 a (b + c) = a x ——– + a x ———-
Solution. b,c
we have , a(b+c)=a x b + a x c [using left distributive law]

Question. 37 (a-b) ————- =( { a }^{ 2 }-2ab+{ b }^{ 2 })
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-11

Question. 38 ({ a }^{ 2 }-{ b }^{ 2 })=(a+b)—————-
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-12

Question. 39 ({{(a-b)}^{2}})+—————-=({ a }^{ 2 }-{ b }^{ 2 })
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-18

Question. 40 ({{(a+b)}^{2}})-2ab=————- + ———–.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-13

Question. 41 (x+a)(x+b)=({ x }^{ 2 }) + (a+b) x + ———–.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-14

Question. 42 The product of two polynomials is a ————–.
Solution. Polynomial
As the product of two polynomials is again a polynomial.

Question. 43 Common factor of ax2 + bx is——————.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-15

Question. 44 Factorised form of 18mn + 10mnp is —————–.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-16

Question. 45 Factorised form of 4({ y }^{ 2 }) – 12y + 9 is———– .
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-17

Question. 46 (38{ x }^{ 2 }{ y }^{ 2 }zdiv 19x{ y }^{ 2 }) is equal to———–.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-1

Question. 47 Volume of a rectangular box with length 2x, breadth 3y and height 4z is ——.
Solution. 24 xyz
We know that, the volume of a rectangular box,
V = Length x Breadth x Height = 2x x 3y x 4z = (2 x 3 x 4) xyz = 24 xyz

Question. 48 ( 6{ 7 }^{ 2 }-3{ 7 }^{ 2 }) =(67 -37) x ———–=————.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-2

Question. 49 ( { 103 }^{ 2 }-{ 102 }^{ 2 })=————- x (103-102)=————–.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-3

Question. 50 Area of a rectangular plot with sides 4({ y }^{ 2 }) and 3({ y }^{ 2 }) is————–.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-4

Question. 51 Volume of a rectangular box with l = b = h = 2x is ———-.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-5

Question. 52 The numerical coefficient in -37abc is————–.
Solution. -37
The constant term (with their sign) involved in term of an algebraic expression is called the numerical coefficient of that term.

Question. 53 Number of terms in the expression ({ a }^{ 2 }) and + bc x d is –.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-6

Question. 54 The sum of areas of two squares with sides 4o and 4b is————-.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-7

Question. 55 The common factor method of factorisation for a polynomial is based on————-property.
Solution.Distributive
In this method, we regroup the terms in such a way, so that each term in the group contains a common literal or number or both.

Question. 56 The side of the square of area 9({ y }^{ 2 }) is————.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-8

Question. 57 On simplification, (frac { 3x+3 }{ 3 }) =————.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-9

Question. 58 The factorisation of 2x + 4y is————-.
Solution. 2 (x + 2y)
We have, 2x + 4y = 2x + 2 x 2y = 2 (x + 2y)

True/False
In questions 59 to 80, state whether the statements are True or False
Question. 59 ({{(a+b)}^{2}}={{a}^{2}}+{{b}^{2}}).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-10

Question. 60 ({{(a-b)}^{2}}={{a}^{2}}-{{b}^{2}}).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-11

Question. 61 (a+b) (a-b)=({{a}^{2}}-{{b}^{2}})
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-12

Question. 62 The product of two negative terms is a negative term.
Solution.False
Since, the product of two negative terms is always a positive term, i.e. (-) x (-) = (+).

Question. 63 The product of one negative and one positive term is a negative term.
Solution.True
When we multiply a negative term by a positive term, the resultant will be a negative term, i-e. (-) x (+) = (-).

Question. 64 The numerical coefficient of the term -6({ x }^{ 2 }{ y }^{ 2 }) is -6.
Solution. True
Since, the constant term (i.e. a number) present in the expression -6({ x }^{ 2 }{ y }^{ 2 }) is -6.

Question. 65 ({ p }^{ 2 })q+({ q }^{ 2 })r+({ r }^{ 2 })q is a binomial.
Solution. False
Since, the given expression contains three unlike terms, so it is a trinomial.

Question. 66 The factors of ({ a }^{ 2 }) – 2ab + ({ b }^{ 2 })are (a + b) and (a + b).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-13

Question. 67 h is a factor of (2pi (h+r)).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-14

Question. 68 Some of the factors of (frac { { n }^{ 2 } }{ 2 } +frac { n }{ 2 }) are (frac { 1 }{ 2 } n) and (n+1).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-15

Question. 69 An equation is true for all values of its variables.
Solution. False
As equation is true only for some values of its variables, e.g. 2x – 4= 0 is true, only for x =2.

Question. 70 ({ x }^{ 2 }) + (a+b)x +ab =(a+b)(x +ab)
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-16

Question. 71 Common factors of (11p{ q }^{ 2 },121{ p }^{ 2 }{ q }^{ 3 },1331{ p }^{ 2 }q) is (11{ p }^{ 2 }{ q }^{ 2 })
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-17

Question. 72 Common factors of 12 (11{ a }^{ 2 }{ b }^{ 2 }) +4a({ b }^{ 2 }) -32 is 4.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-18

Question. 73 Factorisation of -3({ a }^{ 2 })+3ab+3ac is 3a (-a-b-c).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-19

Question. 74 Factorised form of ({ p }^{ 2 })+30p+216 is (p+18) (p-12).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-20

Question. 75 The difference of the squares of two consecutive numbers is their sum.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-21

Question. 76 abc + bca + cab is a monomial.
Solution. True
The given expression seems to be a trinomial but it is not as it contains three like terms which can be added to form a monomial, i.e. abc + abc + abc = 3abc

Question. 77 On dividing (frac { p }{ 3 }) by (frac { 3 }{ p }) ,the quotient is 9
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-22

Question. 78 The value of p for 5({ 1 }^{ 2 })-4({ 9 }^{ 2 })=100 p is 2.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-23

Question. 79 ((9x-51)div 9) is x-51.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-24

Question. 80 The value of (a+1) (a-1)(({ a }^{ 2 }) +1) is ({ a }^{ 4 })-1.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-and-factorisation-25

Question. 81 Add:
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-1
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-2
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-3
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-4

Question. 82 Subtract
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-5
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-6
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-7
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-8

Question. 83 Multiply the following:
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-9
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-10
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-11
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-12
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-13
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-14
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-15
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-16

Question. 84 Simplify
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-17
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-18
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-19
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-20
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-21
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-22

Question. 85 Expand the following, using suitable identities.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-23
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-24
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-25
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-26
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-27
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-28

Question. 86 Using suitable identities, evaluate the following:
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-29
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-30
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-31
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ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-34
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-35

Question. 87 Write the greatest common factor in each of the following terms.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-36
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-37
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-38
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-39
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-40

Question. 88 Factorise the following expressions.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-41
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-42
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-43
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-44
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-45

Question. 89Factorise the following, using the identity,({{a}^{2}}+2ab+{{b}^{2}}={{(a+b)}^{2}})
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-80
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-81
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-82
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Question. 90 Factorise the following, using the identity,({{a}^{2}}-2ab+{{b}^{2}}={{(a-b)}^{2}})
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-46
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-47
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-48

Question.  91 Factorise the following
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-49
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-50
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ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-52

Question.  92 Factorise the following using the identity ,({{a}^{2}}-{{b}^{2}})=(a+b)(a-b).
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-53

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-54
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-55

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-56

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-57

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-58

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ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-60

Question. 93 The following expressions are the areas of rectangles. Find the possible lengths and breadths of these rectangles.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-61
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-62

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-63

Question. 94 Carry out the following divisions:
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-64
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-65

Question. 95 Perform the following divisions:
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-66
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-67

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-68

Question. 96 Factorise the expressions and divide them as directed.

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-69
Solution.

ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-70

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Question. 97 The area of a square is given by 4({{x}^{2}})+ 12xy + 9({{y}^{2}}). Find the side of the square.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-73
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-74

Question. 98 The area of a square is  9({{x}^{2}}) + 24xy + 16({{y}^{2}}). Find the side of the square.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-77

Question. 99 The area of a rectangle is ({{x}^{2}}) + 7x + 12. If its breadth is (x + 3), then find its length.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-78

Question. 100 The curved surface area of a cylinder is (2pi ({ y }^{ 2 }-7y+12)) and its radius is (y – 3). Find the height of the cylinder (CSA of cylinder = (2pirh))
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-79

Question. 101 The area of a circle is given by the expression ( pi { x }^{ 2 }+6pi x+9pi ). Find the radius of the circle.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-1

Question.102 The sum of first n natural numbers is given by the expression (frac { { n }^{ 2 } }{ 2 } +frac { n }{ 2 }) Factorise this expression.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-2

Question.103 The sum of (x + 5) observations is ({ x }^{ 4 }) – 625. Find the mean of the observations.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-3

Question.104 The height of a triangle is ({ x }^{ 4 }) + ({ y }^{ 4 }) and its base is 14xy. Find the area of the triangle.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-4

Question.105 The cost of a chocolate is Rs (x + 4) and Rohit bought (x + 4) chocolates. Find the total amount paid by him in terms of x. If x = 10, find the amount paid by him.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-5

Question.106 The base of a parallelogram is (2x + 3) units and the corresponding height is (2x – 3) units. Find the area of the parallelogram in terms of x. What will be the area of a parallelogram of x = 30 units?
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-6

Question.107 The radius of a circle is 7ab – 7be – 14ac . Find the circumference of the circle,( (pi =frac { 22 }{ 7 } ))
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-7

Question.108 If p + q = 12 and pq = 22, then find ({ p }^{ 2 }) + ({ q }^{ 2 }) .
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-8

Question.109 If a + b = 25 and ({ a }^{ 2 }) + ({ b }^{ 2 }) then find ab.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-9

Question.110 If x – y = 13 and xy = 28, then find ({ x }^{ 2 }) + ({ y }^{ 2 }).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-10

Question.111 If m – n = 16 and ({ m }^{ 2 }) + ({ n }^{ 2 }) = 400, then find mn.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-11

Question.112 If ({ a }^{ 2 }) + ({ b }^{ 2 }) = 74 and ab = 35, then find a + b ?
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-12
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-13

Question.113 Verify the following:
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-14
Solution.
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Question.114 Find the value of a, if
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-18
Solution.
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ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-20

Question.115 What should be added to 4c (-a + b + c) to obtain 3a(a + b + c) – 2b (a – b + c)?
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-21
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-22

Question.116 Subtract b(({ b }^{ 2 }) + b – 7) + 5 from 3({ b }^{ 2 }) – 8 and find the value of expression obtained for b = – 3.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-23

Question.117 If x – (frac { 1 }{ x }) = 1, then find the value of ({ x }^{ 2 }+frac { 1 }{ { x }^{ 2 } }) .
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-24

Question.118 Factorise ({ x }^{ 2 }+frac { 1 }{ { x }^{ 2 } } +2-3x-frac { 3 }{ x }).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-25

Question.119 Factorise ({ p }^{ 4 }+{ q }^{ 4 }+{ p }^{ 2 }{ q }^{ 2 }).
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-26

Question.120 Find the value of
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-27
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-28

Question.121 The product of two expressions is ({ x }^{ 5 }) + ({ x }^{ 3 })+ x . If one of them is ({ x }^{ 2 }) + x + 1, find the other.
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-29

Question.122 Find the length of the side of the given square, if area of the square is 625sq units and then find the value of x.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-30
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-31

Question.123 Take suitable number of cards given in the adjoining diagram [G(x x x) representing ({ x }^{ 2 }), R (x x 1) representing x and Y (1 x 1) representing 1] to factorise the following expressions, by arranging to cards in the form of rectangles: (i) 2({ x }^{ 2 }) + 6x + 4 (ii) ({ x }^{ 2 }) + 4x + 4. Factorise 2({ x }^{ 2 }) + 6x + 4 by using the figure.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-32
Calculate the area of figure.
Solution. The given information is incomplete for solution of this question.

Question.124 The figure shows the dimensions of a wall having a window and a door of a room. Write an algebraic expression for the area of the wall to be painted.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-33
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-34

Question.125 Match the expressions of column I with that of column II
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-35
Solution.
ncert-exemplar-problems-class-8-mathematics-algebraic-expressions-identities-factorisation-36

NCERT Exemplar Solutions

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