(-3 - 5i)(-3 + 5i) = - QAmmunity.org

asked Sep 4, 2017 168k views

3 votes

(-3 - 5i)(-3 + 5i) =

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6 votes

Hello,
You don't know (a-b)(a+b)=a²-b²?

(-3)²=9
(5i)²=-25
Answer 9 +25=34

Favio answered Sep 6, 2017

by Favio

8.0k points

5 votes

(-3 - 5i)(-3 + 5i)
-3(-3 + 5i) - 5i(-3 + 5i)
-3(-3) - 3(5i) - 5i(-3) - 5i(5i)
9 - 15i + 15i - 25i²
9 - 25(-1)
9 + 25
34

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