What is the coefficient of $x^2$ in the expansion of $(x+2)^3$ ?

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Answer 1 · 2016-10-28T13:02:24

The coefficient of $x^2$ in the expansion of $(x+2)^3$ is $6$

Binomial expansion of $(x+a)^3$ is

$x^3+^3C_1x^2a+^3C_2xa^2+^3C_3a^3$

Hence coefficient of $x^2$ in $(x+2)^3$ is

$color(white)+^3C_1xx2$

= $3xx2=6$

What is the coefficient of x^2x^2 in the expansion of (x+2)^3(x+2)^3?