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Question:

If $f(x)=x^{3}+4 x^{2}-x$, find $f(A)$, where $A=\left[\begin{array}{rrr}0 & 1 & 2 \\ 2 & -3 & 0 \\ 1 & -1 & 0\end{array}\right]$

Solution:

Given : $f(x)=x^{3}+4 x^{2}-x$