How do you simplify $(2+6i)(2-9i)$ ?

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Answer 1 · 2015-11-30T01:28:58

$58-6i$

You can expand the expression by multiply it or (FOIL).

Given : $" "(2+6i)*(2-9i)$

$=>4- 18 i +12 i -54i^2$

$=>4- 6i -54i^2" "$ Combined like terms

Remember $" "color(red)(i^2 = -1)$

Replace $-1$ for $i^2$

$=> 4-6i -54(color(red)(-1))$
$=>4-6i + 54$

$=>58-6i$

How do you simplify (2+6i)(2-9i)(2+6i)(2-9i)?