1.

The coefficient of x in the expansion of (x + 3)3 is (A) 1 (B) 9 (C) 18 (D) 27

Answer»

(d) 27

Now, (x + 3)3 = x3 + 33 + 3x (3)(x + 3)
[using identity, (a + b)3 = a3 + b3 + 3ab (a + b)]

= x3 + 27 + 9x (x + 3)

= x3 +27 + 9x2+27x 

Hence, the coefficient of x in (x + 3)3 is 27.



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