Coefficient of x in expansion of (x+3)^{3} is

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2. Polynomials

easy

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

A

$1$

B

$9$

C

$27$

D

$18$

Solution

Using $(a+b)^{3}=a^{3}+b^{3}+3 a b(a+b),$ we get

$(x+3)^{3}=x^{3}+3^{3}+3 \times x \times 3(x+3)$

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

Therefore, the coefficient of $x$ is $27 .$

Hence, $(c)$ is the correct answer.

Standard 9

Mathematics

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