Answer
$-314928$
Work Step by Step
By using the binomial theorem we can expand the algebraic expression in the form of:
$(ax+b)^n=\binom{n}{0}a^nb^0x^n+\binom{n}{1}a^{n-1}b^1x^{n-1}+...+\binom{n}{n-i}a^{i}b^{n-i}x^{i}+...+\binom{n}{n-1}a^1b^{n-1}x^1+\binom{n}{n}a^0b^nx^0$
There, we can see that the coefficient of $x^i$ is $\binom{n}{n-i}a^{i}b^{n-i}$.
In this case, $a=2$, $b=-3$, $n=9$, $i=2$; therefore, the coefficient will be:
$\binom{9}{9-2}2^2(-3)^{9-2}=\binom{9}{7}2^2(-3)^7=36\times 4\times -2187=-314928$
