How do you simplify $(-5-4i)(3-7i)$ ?

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Answer 1 · 2016-06-23T16:07:27

$-43 +23i$

To simplify $(-5-4i)(3-7i)$

Begin by using FOIL (First Outers Inners Lasts) to distribute and multiply the binomials.

$-(5)(3) -(5)(-7i) -(4i)(3)-(4i)(-7i)$

$-15 +35i -12i+28i^2$

In Euler's notation $i^2=-1$

$-15 +35i -12i+28(-1)$

$-15 +35i -12i-28$

Combine like terms

$-43 +23i$

How do you simplify (-5-4i)(3-7i)(-5-4i)(3-7i)?