# Math Help - Help with just a few?

1. ## Help with just a few?

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

1) a^2 - 416 = 0

a= or a=

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

3) (5i)^3

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

2. Originally Posted by knowledgekick
I'm doing my homework and these are a few I need help with.

1) a^2 - 416 = 0

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

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

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

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

3) (5i)^3

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

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

just combine like terms for this one
...