Originally Posted by

**knowledgekick** I'm doing my homework and these are a few I need help with.

1) a^2 - 416 = 0

$\displaystyle \textcolor{red}{(a+\sqrt{416})(a-\sqrt{416}) = 0}$

for simplification purposes, note that $\displaystyle \textcolor{red}{416 = 16 \cdot 26}$

2) (4+7i)(3+2i)

multiply it out ... remember that $\displaystyle \textcolor{red}{i^2 = -1}$

3) (5i)^3

hint ... $\displaystyle \textcolor{red}{i^3 = i^2 \cdot i}$

4) (-5+5i) + (7-7i)

just combine like terms for this one