NCERT Solutions Class 8 Maths Chapter 9 Algebraic Expressions and Identities Exercise 9.2

NCERT Solutions Class 8 Maths Chapter 9 Algebraic Expressions and Identities Exercise 9.2

 

Introduction:

In this exercise/article we will learn about multiplication of algebraic expression. Multiplying a monomials by a monomials and multiply two monomials and multiplying three or more monomials find out factor of monomials. [ using identity = volume of rectangle = Length × Breadth × Height ] only on using formula and multiply do in this exercise .

 

NCERT Solutions Class 8 Maths Chapter 9 Algebraic Expressions and Identities :

 

Class 8 Maths Exercise 9.2 (Page-143)

 

Q1. Find the product of the following pairs of monomials.

(i) 4 , 7p

Solution :

We have 4 , 7p

we know very well

= 4 × 7p

= 28p

So, answer is 28p

(ii) - 4p , 7p

Solution :

We have - 4p , 7p

we know very well

= - 4p × 7p

= - 28p2

So, answer is - 28p2

(iii) - 4p , 7pq

Solution :

We have  - 4p , 7pq

we know very well

=  - 4p × 7pq

= - 28p2q

So, answer is - 28pq

(iv) 4p3 , - 3p

Solution :

We have 4p3 , - 3p

we know very well

= 4p3 × - 3p

= - 12p4

So, answer is - 12p4

(v) 4p , o

Solution :

We have 4p , o

we know very well

= 4p × o

= 0

So, answer is 0

Q2. Find the area of rectangles with the following of monomials as their lengths and breadths respectively.

( p , q ) ; ( 10m , 5n ) ; ( 20x2 , 5y2 ) ; ( 4x , 3x2 ) ; ( 3mn , 4np )

Solution :

We have given ( p , q )

here, Length = p,    breadth = q

Area of rectangle = length × breadth

= p × q

= pq

We have given ( 10m , 5n )

here, Length = 10m,    breadth = 5n

Area of rectangle = length × breadth

= 10m × 5n

= 50mn

We have given ( 20x2 , 5y2 )

here, Length = 20x2,    breadth = 5y2

Area of rectangle = length × breadth

= 20x2 × 5y2

= 100x2y2

We have ( 4x , 3x2 )

here, Length = 4x,    breadth = 3x2

Area of rectangle = length × breadth

= 4x × 3x2

= 12x3

We have ( 3mn , 4np )

here, Length = 3mn,    breadth = 4np

Area of rectangle = length × breadth

= 3mn × 4np

= 12mn2p

Class 8 Maths Chapter 9 Exercise 9.2

Q3. Complete the table products.

NCERT Solutions Class 8 Maths Chapter 9 Algebraic Expressions and Identities Exercise 9.2 Q.3

Solution :

Multiply the first monomial by the second monomials

NCERT Solutions Class 8 Maths Chapter 9 Algebraic Expressions and Identities Exercise 9.2 Q.3

Q4. Obtain the volume of rectangular boxes with the following length, breadth and height respectively.

(i) 5a, 3a2 , 7a4

Solution :

We have 5a, 3a2 , 7a4

here, Length = 5a,  breadth = 3a2  and  height = 7a4

Volume of rectangle = length × breadth × height

= 5a × 3a2 × 7a4

= 105a7

So, answer is 105a7

(ii) 2p, 4q, 8r

Solution :

We have 2p, 4q, 8r

here, Length = 2p,  breadth = 4q  and  height = 8r

Volume of rectangle = length × breadth × height

= 2p × 4q × 8r

= 64pqr

So, answer is 64pqr

(iii) xy, 2x2y, 2xy2

Solution :

We have xy, 2x2y, 2xy2

here, Length = xy,  breadth = 2x2y  and  height = 2xy2

Volume of rectangle = length × breadth × height

= xy × 2x2y × 2xy2

= 4x4y4

So, answer is 4x4y4

(iv) a, 2b, 3c

Solution :

We have a, 2b, 3c

here, Length = a,  breadth = 2b  and  height = 3c

Volume of rectangle = length × breadth × height

= a × 2b × 3c

= 6abc

So, answer is 6abc

Q5. Obtain the product of

(i) xy, yz, zx

Solution :

We have xy, yz, zx

multiply all these

= xy × yz × zx

= x2y2z2

So, answer is x2y2z2

(ii) a, - a2 , a3

Solution :

We have a, - a2 , a3

multiply all these

= a × - a2 × a3

= - a6

So, answer is - a6

(iii) 2, 4y, 8y2 , 16y3

Solution :

We have 2, 4y, 8y2 , 16y3

multiply all these

= 2 × 4y × 8y2 × 16y3

= 1024y6

So, answer is 1024y6

(iv) a, 2b, 3c, 6abc

We have a, 2b, 3c, 6abc

multiply all these

= a × 2b × 3c × 6abc

= 36a2b2c2

= So, answer is 36a2b2c2

(v) m, - mn, mnp

Solution :

We have m, - mn, mnp

multiply all these

= m × - mn × mnp

= - m3n2p

So, answer is - m3n2p .

 

NCERT Solutions Class 8 Maths Chapter 9 Algebraic Expressions and Identities :

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