Question 240476
Hint: if we let {{{z=a+4}}} and apply the appropriate substitutions, we go from {{{(a+4)^2-2(a+4)+1}}} to {{{z^2-2z+1}}}. Now factor {{{z^2-2z+1}}}. Once you have {{{z^2-2z+1}}} factored out, plug {{{z=a+4}}} back in.