Table of Contents

Toggle## Class 8, Maths, Chapter 9, Exercise 9.2, Solutions

**Q.****1. Find the product of the following pairs of monomials.**

**(i) 4, 7p **

**(ii) – 4p, 7p **

**(iii) – 4p, 7pq **

**(iv) 4p ^{3}, – 3p**

**(v) 4p, 0**

**Ans: **

(i) Product of 4, 7p = 4×7P=28 P

(ii) Product of –4p,7p = (– 4p) × (7p) = -28 P^{2}

(iii) Product of – 4p,7pq = (–4p)×(7pq) = -28 p^{2}q

(iv) Product of 4p^{3},– 3p = (4p^{3}) × (–3p) = -12p^{4}

(v) Product of 4p, 0 = (4p) × 0 =0

**Q.****2. Find the areas of rectangles with the following pairs of monomials as their lengths and breadths respectively. (p,q); (10m,5n); (20x ^{2},5y^{2}); (4x,3x^{2}); (3mn,4np)**

**Ans: **Area of rectangle = Length (l) X Breadth (b)

**(i) (p,q)**

Area of rectangle = Length (l) X Breadth (b)

= p×q

=pq square unit

**(ii) (10m,5n)**

Area of rectangle = Length (l) X Breadth (b)

= 10m × 5n

=50 mn square unit

**(iii) (20x ^{2}, 5y^{2})**

Area of rectangle = Length (l) X Breadth (b)

=20x^{2} × 5y^{2 }

= 100 x^{2}y^{2} square unit

**(iv) (4x,3x ^{2}) **

Area of rectangle = Length (l) X Breadth (b)

= 4x × 3x^{2}

= 12 x^{3} square unit

**(v) (3mn,4np)**

Area of rectangle = Length (l) X Breadth (b)

=3mn × 4np

= 12 mn^{2}p squre unit

**Q.3. Complete the table of products**

**Q.4. Obtain the volume of rectangular boxes with the following length, breadth and height respectively.**

**(i) 5a,3a ^{2},7a^{4} **

**(ii) 2p,4q,8r **

**(iii) xy,2x ^{2}y,2xy^{2} **

**(iv) a,2b,3c**

**Ans: **

Volume of rectangular box = Length x Breadth x Height

**(i) 5a,3a ^{2}, 7a^{4}**

Volume of rectangular box = Length X Breadth X Height

= 5a × 3a^{2} × 7a^{4}

=105 a^{7}

**(ii) 2p,4q,8r **

Volume of rectangular box = Length X Breadth X Height

=2p × 4q × 8r

=64 pqr

**(iii) xy,2x ^{2}y, 2xy^{2} **

Volume of rectangular box = Length X Breadth X Height

=xy × 2x^{2}y × 2xy^{2}

=4x^{4}y^{4}

**(iv) a,2b,3c**

Volume of rectangular box = Length X Breadth X Height

= a × 2b × 3c

=6 abc

**Q.5. Obtain the product of**

**(i) xy,yz,zx **

**(ii) a,– a ^{2}, a^{3} **

**(iii) 2,4y,8y ^{2},16y^{3}**

**(iv) a,2b,3c,6abc **

**(v) m,– mn,mnp**

**Ans: **

**(i) Product of xy,yz,zx **

⇒ xy × yz × zx

⇒ x × x × y × y × z × z

⇒ x^{2}y^{2}z^{2 }**(Ans.) **

** **

**(ii) Product of a,– a ^{2}, a^{3} **

⇒ a×(– a^{2}) × a^{3}

= a^{6} ^{ }**(Ans.)**

**(iii) Product of 2,4y,8y ^{2}, 16y^{3}**

⇒ 2 × 4y × 8y^{2} × 16y^{3}

⇒ (2×4×8×16) × (y × y^{2} × y^{3})

⇒ 1024 y^{6} ^{ }**(Ans.)**

** **

**(iv) Product of a,2b,3c,6abc **

⇒ a × 2b × 3c × 6abc

⇒ (1 × 2 × 3 × 6) × (a × b × c × abc)

= 36 a^{2}b^{2}c^{2} ^{ }**(Ans.)**

** **

**(v) Product of m,– mn,mnp**

⇒ m×( – mn)× mnp

⇒ – m^{2}n × mnp

⇒ -m^{3}n^{2}p ^{ }**(Ans.)**

## NCERT Solutions For Class 8 Maths Chapter 9, Algebraic Expressions and Identities (All Exercises)

**Class 8, Maths, Chapter 9, Algebraic Expressions and Identities **

**Class 8, Maths, Chapter 9, Algebraic Expressions and Identities , Exercise 9.1**

**Class 8, Maths, Chapter 9, Algebraic Expressions and Identities , Exercise 9.2** **← You are here**

**Class 8, Maths, Chapter 9, Algebraic Expressions and Identities , Exercise 9.3**

**Class 8, Maths, Chapter 9, Algebraic Expressions and Identities , Exercise 9.4**

**Class 8, Maths, Chapter 9, Algebraic Expressions and Identities , Exercise 9.5**