Ncert Solutions For Class 8 Maths Ex 9.2

Ncert Solutions For Class 8 Maths Chapter 9 Ex 9.2

Q.1.For the following pairs of monomials find the product.

(I)5, 6a

Answer: 5×6×a=30a

(II)-5a, 6 a

Answer: 5a×6a×=5×a×6×a=(5×6)×(a×a)=30a2

(III) )-5a, 6 ab

Answer: 5a×6ab×=5×a×6×a×b=(5×6)×(a×a×b)=30a2b

(IV) ) 5a3,- 4 a

Answer: 5a3×4a=5×(4)×a×a×a×a=20a4

(V)5a, 0

Answer: 5a×0=5×a×0=0

 

Q.2.calculate the area of rectangles.Where the pairs of monomials  are lengths and breadths respectively.

NOTE: area of rectangle =length×breadth

  • (a, b)

Area= a×b=ab

  • (10a, 5b)

Area = 10a×5b=10×5×a×b=50ab

  • (20p2,5q2)

Area = 20p2×5q2=20×5×p2×q2=100p2q2

  • (4a,3a2)

Area = 4a×3a2=4×3×a×a2=12a3

  • (4ab,3bc)

Area= 4ab×3bc=4×3×a×b×b×c=12ab2c

 

Q.3.Complete the table of product.

First monomial

Second monomial

 

2x

-5y 3x2 -4xy 7x2y 9x2y2
2x 4x2
-5y 15x2y
3x2
-4xy

 

Solution:

First monomial

Second monomial

 

2x

-5y 3x2 -4xy 7x2y 9x2y2
2x 4x2 10xy 6x3 8x2y 14x3y 18x3y2
-5y   10xy 15x2y 15x2y 20xy2 35x2y2 45x2y3
3x2 6x3 15x2y 9x4 12x3y 21x4y 27x4y2
-4xy 8x2y 20x2y 12x3y 16x2y2 28x3y2 36x3y3

 

 

Q.4.Rectangular boxes with the length ,breadth , and height are given respectively. Find the volume.

(I) 5x,3x2,7x4

Answer: Volume=5x×3x2×7x4=5×3×7×x×x2×x4=105x7

(II)2p, 4q, 8r

Answer: Volume=2p×4q×8r=2×4×8×p×q×r=64pqr

(III) ab,2a2b,2ab2

Answer:  Volume=ab×2a2b×2ab2=2×2×ab×a2b×ab2=4a4b4

(IV)p, 2q, 3r

Answer:  Volume=p×2q×3r=2×3×p×q×r=6pqr

 

Q.5.Find the Product of the following:

(I)ab, bc, ca

Answer: ab×bc×ca= a2b2c2

(II) x,x2,x3

Answer: x×(x2)×x3=x6

(III) 2,4a,8a2,16a3

Answer: 2×4a×8a2×16a3=1024a6

(IV)x, 2y, 3z, 6xyz

Answer: x×2y×3z×6xyz=36x2y2z2

(V)m, -mn, mnp

Answer: m×mn×mnp=m3n2p