The coefficient of x in (x − 3y)3 is:
Answer & explanation
Correct answer: option 2
(a - b)3 = a3 - b3 - 3ab(a-b)
(x – 3y)3
= x3 – (3y)3 – 3 × x × 3y (x – 3y)
= x3 – 27y3 – 9x2y + 27xy2
So, the coefficient of x = 27y2
The coefficient of x in (x − 3y)3 is:
Correct answer: option 2
(a - b)3 = a3 - b3 - 3ab(a-b)
(x – 3y)3
= x3 – (3y)3 – 3 × x × 3y (x – 3y)
= x3 – 27y3 – 9x2y + 27xy2
So, the coefficient of x = 27y2