Respuesta :

(4-5i)(-5+i)
= 4x-5 + 4xi + -5i x -5 + -5ixi
= -20 + 4i +25i -5i²
Use Foil, or the box method to multiply
4 -5i
-5 -20 25i
i 4i -5i^2

Combine like terms
-5i^2 +29i -20

By definition i^2 is equal to -1
Plug it in
-5(-1) +29i -20
29i -20 + 5

ANSWER:
29i -15

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