Question

How can you rewrite the expression (8-5i)^2 in the form of a +bi

Answer 1

$\bf \textit{recall that }i^2=-1\\\\ -------------------------------\\\\ (8-5i)^2\implies (8-5i)(8-5i)\implies 64-40i-40i+(5i)^2 \\\\\\ 64-80i+(5^2i^2)\implies 64-80i+(25\cdot -1)\implies 64-80i+(-25) \\\\\\ 64-80i-25\implies 39-80i$