Question

If the complex number x = 3 + bi and |x|2 = 13, which is a possible value of b?

Answer 1

We know that |x|² = 13 and x = 3+bi:

(3+bi)² = 13

3² + b² = 13

9 + b² = 13

Subtract 9 from each side:

9 + b² - 9 = 13 - 9

b² = 4

Take the square root of each side:

√b² = √4

b = 2