The coefficient of x in the expansion of

Question:

The coefficient of $x$ in the expansion of $(x+3)^{3}$ is

(a) 1

(b) 9

(c) 18

(d) 27

Solution:

$(x+3)^{3}$

$=x^{3}+3^{3}+9 x(x+3)$

$=x^{3}+27+9 x^{2}+27 x$

So, the coefficient of $x$ in $(x+3)^{3}$ is 27 .

Hence, the correct answer is option (d).