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# The $10^{th}$ term in the expansion of $(x-1)^{11}$ (in decreasing power of $x$) is

$\begin{array}{1 1}(A)\;-x\\(B)\;-11x\\(C)\;-x^2\\(D)\;-11C_2x^2\end{array}$

Toolbox:
• $T_{r+1}=nC_ra^{n-r} b^r$
$T_{10}=T_{9+1}=11C_9(x)^{11-9}(-1)^9$
$\Rightarrow 11C_9x^2$
$\Rightarrow -11C_2x^2$
Hence (D) is the correct answer.