Simplify : (x + y)3 - (x - y)3 - 6y(x2 - y2)
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e.8y3
Formula used
(X – Y)³ = X³ – Y³– 3XY(X – Y)
(X + Y)³ = X³ + Y³ + 3XY(X + Y)
Given that
(x + y)3 - (x - y)3 - 6y(x2 - y2)
= x³ + y³ + 3x2y + 3 y2x - ( x³ – y³– 3x2y + 3y2x) - 6 yx2 + 6y3
= x³ + y³ + 3x2y + 3 y2x - x³ + y³+ 3x2y - 3y2x - 6 yx2 + 6y3
= 8 y3