Question

H e l p

Find the coefficient of the a^2 term after expanding the following.
(-5a+5)^3

Answer 1

`~\hfill \textit{Binomial Theorem Expansion}\hfill ~\\\\ {\Large \begin{array}{llll} (-5a+5)^(3) \end{array}}~\hspace{4em} \begin{array}{cccl} term&coefficient&value\\ \cline{1-3}&\\ 1 & 1 & (-5a)^(3)~(+5)^(0)\\ \boxed{2} & 3 & (-5a)^(2)~(+5)^(1)\\ 3 & 3 & (-5a)^(1)~(+5)^(2)\\ 4 & 1 & (-5a)^(0)~(+5)^(3) \end{array} \\\\[-0.35em] ~\dotfill\\\\ 3(-5a)^2(5)^1\implies 3(25a^2)(5)\implies 3(125a^2)\implies 375a^2`