The coefficient of x in (x - 3y)3 is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 27y2.
| Understanding/Application |
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(a - b)3 = a3 - b3 - 3ab(a - b) (x - 3y)3 = x3 - (3y)3 - 3(x)(3y) (x - 3y) |
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= x3 - 27y3 - 9xy(x - 3y) = x3 - 27y3 - 9x2y + 27xy2 Thus, the coefficient of x = 27y2 |