How do you simplify (4-5i)(4+i)?

1 Answer
Jim G.
Nov 1, 2016

21-16i

Explanation:

Distribute the brackets using, for example, the FOIL method.

(4-5i)(4+i)=16+4i-20i-5i^2=16-16i-5i^2

color(orange)"Reminder " color(red)(bar(ul(|color(white)(2/2)color(black)(i^2=(sqrt(-1))^2=-1)color(white)(2/2)|)))

rArr16-16i-5i^2=16-16i+5=21-16i

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