Reviewed CSCA Mathematics question · Easy

What is the value of (2 - i)(3 + 2i)?

8 + i
8 - i
4 + i
4 - i

Show the answer and explanation

Correct answer

A. 8 + i

Principle or equation

To multiply complex numbers, use the distributive property and the fact that i^2 = -1.

Why this answer is correct

(2 - i)(3 + 2i) = 6 + 4i - 3i - 2i^2 = 6 + i - 2(-1) = 6 + i + 2 = 8 + i.

Example

For (1 + i)(2 - i) = 2 - i + 2i - i^2 = 2 + i + 1 = 3 + i.

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