Multiply (7 + 5i)(3 - 9i) Type answer in the form a + bi

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Remember...

i = i
i² = -1
i³ = -i
i⁴ = 1
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(7 + 5i)(3 - 9i)

FOIL

21 - 63i + 15i - 45i²

21 - 48i - 45i²

21 - 48i - 45(-1)

21 - 48i + 45

66 - 48i <---

(7+5i)(3-9i) = 21 -63i +15i -45i^2 =21-48i -45(-1) =21 -48i +45 =66 -48i

a+bi=(7 + 5i)(3 - 9i)
a+ bi=21+45--63i+15i

a+bi=66-48i

===>a=66

& b=--48