In this page we have Class 8 maths exercise 9.4 solutions for
Algebraic Expressions .This exercise has questions about multiplication of polynomials by polynomials. Hope you like them and do not forget to like , social share
and comment at the end of the page.
Class 8 maths exercise 9.4 solutions
Question 1
Multiply the binomials.
(i) (2x + 5) and (4x – 3)
(ii) (y – 8) and (3y – 4)
(iii) (2.5l – 0.5m) and (2.5l + 0.5m)
(iv) (a + 3b) and (x + 5)
(v) (2pq + 3q2) and (3pq – 2q2) Answer:
Let ( a+b) (c+d) to be done
then
(a+b) (c+d)= a(c+d) + b( c+d)
=a x c+a x d+b x c+b x d
We will use the same concept in all the question below
(i) (2x + 5)(4x - 3)
= 2x x 4x - 2x x 3 + 5 x 4x - 5 x 3
= 8x² - 6x + 20x -15
= 8x² + 14x -15
(ii) ( y - 8)(3y - 4)
= y x 3y - 4y - 8 x 3y + 32
= 3y2 - 4y - 24y + 32
= 3y2 - 28y + 32
(iii) (2.5l - 0.5m)(2.5l + 0.5)
Using (a+b)(a-b) = a2 - b2
We get = 6.25l2 - 0.25m2
(iv) ax + 5a + 3bx + 15b
v) 2pq x 3pq - 2pq x 2q2 + 3q2x 3pq - 3q2x 2q2
= 6p2q2 - 4pq3 + 9pq3 - 6q4
= 6p2q2 - 5pq3 - 6p4
Question 2
Find the product.
(i) (5 – 2x) (3 + x)
(ii) (x + 7y) (7x – y)
(iii) (a2+ b) (a + b2)
(iv) (p2– q2) (2p + q) Answer:
(i) 15 + 5x - 6x - 2x2
= 15 - x - x 2
(ii) 7x2 - xy + 49xy - 7y2
= 7x2 - 7y2 + 48xy
(iii) a2 x a + a2 x b + a x b + b3
= a3 + a2b + ab + b3
= a3 + b3 + a2b + ab
(iv) 2p3 + p2q - 2pq2 - q3
= 2p3 - q3 + p2q - 2pq2
Question 3
Simplify.
(i) (x2– 5) (x + 5) + 25
(ii) (a2+ 5) (b3+ 3) + 5
(iii) (a + b) (c – d) + (a – b) (c + d) + 2 (ac + bd)
(iv) (x + y)(2x + y) + (x + 2y)(x – y)
(v) (x + y)(x2– xy + y2)
(vi) (1.5x – 4y)(1.5x + 4y + 3) – 4.5x + 12y
(vii) (a + b + c)(a + b – c) Answer:
(i) x3 + 5x2 - 5x - 25 + 25
= x3 + 5x2 -5x
(ii) a2b3 + 3a2 + 5b3 + 15 + 5
= a2b3 + 5b3 + 3a2 + 20
(iii) (ac - ad + bc - bd) + (ac + ad - bc - bd) + (2ac + 2bd)
= ac - ad + bc - bd + ac + ad - bc - bd + 2ac + 2bd
= 4ac
(iv) 2x2 + xy + 2xy + y2 + x2 - xy + 2xy - 2y2
= 3x2 + 4xy - y2
(v) x3 - x2y + xy2 + x2y - xy2 + y3
= x3 + y3
(vi) 2.25x2 + 6xy + 4.5x - 6xy - 16y2 - 12y - 4.5x + 12y
= 2.25x2 - 16y2
(vii) a2 + ab - ac + ab + b2 - bc + ac + bc - c2
= a2 + b2 - c2 + 2ab
Summary
Class 8 maths exercise 9.4 solutions has been prepared by Expert with utmost care. If you find any mistake.Please do provide feedback on mail. You can download the solutions as PDF in the below Link also Download Algebraic Expressions Exercise 9.4 as pdf
This chapter 9 has total 5 Exercise 9.1 ,9.2 ,9.3 ,9.4 and 9.5. This is the Fourth exercise in the chapter.You can explore previous exercise of this chapter by clicking the link below
