Question

What is the product of 4-5i and 2+3i

Answer 1

Multiply these as you would any binomial expressions, then replace i² with -1.

(4 -5i)·(2 +3i) = 4·2 +4·3i -5i·2 -5i·3i

... = 8 +12i -10i -15i²

... = 8+15 +2i

... = 23 +2i

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