(3a - 4b)3 is equal to:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 27a3 - 64b3 - 108a2b + 144ab2
⇒ (3a - 4b)3
By the expansion of (x - y)3 = x3 - y3 - 3xy(x - y)
By putting x = 3a & y = 4b
⇒ (3a)3 - (4b)3 - 3(3a)(4b)(3a - 4b)
⇒ 27a3 - 64b3 - 36ab(3a - 4b)
⇒ 27a3 - 64b3 - 108a2b + 144ab2