# Find the $4^{th}$ term in the expansion of $(x-2y)^{12}$

$\begin{array}{1 1}(A)\;-1760\\(B)\;-760x^9\\(C)\;-1760x^9y^3\\(D)\;x^9y^3\end{array}$

Toolbox:
• $(a-b)^n=nC_0a^n-nC_1a^{n-1}b+nC_2a^{n-2}b^2-......+(-1)^nnC_ra^{n-r}b^r+......nC_n(-b)^n$
$4^{th}$ term =$T_{3+1}$ in the expansion of $x+(-2y)^{12}$
$\Rightarrow 12C_3x^{12-3}[-2y]^3$