What is the coefficient of x in the expansion of (3x - 4)3 ?
Answer & explanation
Correct answer: option 3
Given,
(3x – 4)3
(a – b)3 = a3 – b3 – 3ab(a – b)
So,
(3x – 4)3 = (3x)3 – (4)3 – 3 × 3x × 4(3x – 4)
= 27x3 - 64 - 36x(3x – 4)
= 27x3 - 64 - 108x2 + 144x
So, The coefficient of x in (3x – 4)3 = 144