Binomial expansion -
(3x-2)^4
thanks
The binomial theorem:
$\displaystyle (x + y)^n = \displaystyle\sum_{k=0}^{n} \left(\begin{array}{cc}n\\k\end{array}\right) x^{(n-k)} y^k $
$\displaystyle \left(\begin{array}{cc}n\\k\end{array}\right) = \dfrac{n!}{k!(n-k)!} $
Just plug the values in and go.