NCERT Solution For Class 8 Maths Chapter – Algebraic Expression Exercise – 9.4

Q1. Multiply the binomials.

(2x + 5) and (4x – 3)
(y – 8) and (3y – 4)
(2.5l – 0.5m) and (2.5l + 0.5m)
(a + 3b) and (x + 5)
(2pq + 3q²) and (3pq – 2q²)
(3/4 a² + 3b²) and 4(a² – 2/3b²)

Solution:-

(2x + 5) (4x – 3)

= 2x x 4x – 2x x 3 + 5 x 4x – 5 x 3

= 8x² + 14x – 15

( y – 8) (3y – 4)

= y x 3y – 4y – 8 x 3y + 32

= 3y² – 28y + 32

(2.5l – 0.5m) (2.5l + 0.5m)

= 2.5 L X 2.5L + 2.5L X 0.5M – 0.5M X 2.5L – 0.5M X 0.5M

= 6.25L² – 0.25 M²

(IV) (a + 3b) ( x+ 5)

= ax + 5a + 3bx + 15b

(a + 3b) (x + 5)

= ax + 5a + 3bx + 15b

(2pq + 3q²) (3pq – 2q²)

= 6p²q² + 5pq³ – 6q⁴

(3/4 a² + 3b²) and 4(a² – 2/3b²)

= 3a⁴ + 10a²b² – 8b⁴

Q2. Find the product.

( 5 – 2x) (3 + x)
(x + 7y) (7x – y)
(a² + b) ( a + b²)
(p² – q²) (2p + q)

Solution:-

= 5(3 + x ) -2x (3 + x)

= 15 – x – 2x²

= x(7x – y) + 7y (7x – y)

= 7x² – 7y²+ 48xy

= a² (a + b²) + b (a + b²)

= a³ + b³ + a²b² + ab

= p² (2p + q) -q² (2p + q)

= 2p³ – q³ + p²q -2pq²

Q3. Simplify.

(x² – 5) (x + 5) + 25
(a² + 5) (b³ + 3) + 5
(t + s²) (t² – s)
(a + b) (c – d) + (a – b ) ( c + d) + 2(ac + bd)
( x + y )(2x + y ) + (x + 2y)(x – y )
(x + y ) (x² – xy + y²)
(1.5x – 4y) (1.5x + 4y + 3) -4.5x + 12y
( a+ b + c) (a + b – c )

Solution:-

= x³ + 5x² – 5x – 25 + 25

= x³ + 5x² – 5x

= a²b³ + 3a² + 5b³ +15 + 5

= a²b³ + 5b³+ 3a² + 20

= t (t² – s) + s² (t² – s)

= t³ – s³ – st + s²t²

= (a + b )(c – d) + (a – b) (c + d) + 2( ac + bd)

= 4ac

= 2x² +xy + 2xy + y² + x² – xy + 2xy – 2y²

= 3x² + 4xy – y²

= x – x²y + xy² + x²y – xy² + y³

= x³ + y³

= 2.25x² + 6xy + 4.5x – 6xy – 16y² – 12y

= 2.25x² – 16y²

(a + b + c)(a + b – c)

= a² + ab – ac + ab + b² – bc + ac + bc – c²

= a² + b² – c² + 2ab

NCERT Class – 7th Science Textbook Question Answer All Chapters Link