Factorize 9(x + y)2 - 4(x - y)2
A
(x + y)(5x + y)
B
(x + y)2
C
(x + 5y)(5x + y)
D
5(x + y)2
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
9(x + y)2 - 4(x - y)2
Using difference of two squares which says
a2 - b2 = (a + b)(a - b) = 9(x + y)2 - 4(x - y)2
= [3(x + y)]2 - [2(x - y)]-2
= [3(x + y) + 2(x - y) + 2(x - y)][3(x + y) - 2(x - y)]
= [3x +3y + 2x - 2y][3x + 3y - 2x + 2y]
= (5x + y)(x + 5y)
Source: Myschool Past Questions Archive (Record #31453)