Question

If the complex number x = 3 + bi and |x|^2 = 13, which is a possible value of b?
a. 2
b. 4
c. 9
d. 10

Answer 1

(3+bi)*(3-bi)=3^2+b^2 =13
so
b^2=13-9=4
b=+2,-2
both of them are acceptable