How do you multiply (2+i)(2-3i) (2+i)(23i) in trigonometric form?

1 Answer
Oct 21, 2017

7-4i74i

Explanation:

First, we have to know that
i^1=ii1=i
i^2=-1i2=1
i^3=-ii3=i
i^4=1i4=1

Then, we can expend the expression and simplify it with the above rule:

(2+i)(2-3i)(2+i)(23i)
=4-6i+2i-3i^2=46i+2i3i2
=4-4i-3i^2=44i3i2
=4-4i-3(-1)=44i3(1)
=4-4i+3=44i+3
=7-4i=74i

It's the answer! Hope it can help you :)