Factorize 9(x + y)2 – 4(x – y)2
- (x + y)(5x + y)
- (x + y)2
-
(x + 5y)(5x + y)
- 5(x + y)2
The correct answer is: C
Explanation
9(x + y)2 - 4(x - y)2Using 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)