Expand (x/3 + y/5)3 :
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. x3/27 + x2y/15 + xy2/25 + y3/125
(x/3 + y/5)3
By using the identity,
(a + b)3 = a3 + b3 + 3ab(a + b)
⇒ (x/3 + y/5)3 = (x/3)3 + (y/5)3 + 3(x/3)(y/5)(x/3 + y/5)
⇒ x3/27 + y3/125 + (xy/5)((5x + 3y)/15)
⇒ x3/27 + y3/125 + x2y/15 + xy2/25