Answer
$4860x^2$
Work Step by Step
According to the Binomial Theorem we can obtain the $r+1$th term of the expansion of the binomial $(x+y)^n$ by the formula $_nC_rx^{n-r}y^r$.
Hence here it is: (by plugging in $n=6,r=4$ and $2x,-3$): $_6C_4(2x)^{6-4}(-3)^4=15\cdot 4x^2\cdot81=4860x^2$
