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

take |x|2 = 13 divide both sides by 2, |x|=7.5

7.5 =3 +bi
4.5=bi
-4.5i=b or....

Answer 2

|x|=7.5
-7.5 = 3 + bi
-10.5=bi
+10.5i=b

Answer 3

@ChelsH, do you see how I got this?

Answer 4

I don't fully understand it..

Answer 5

The answer doesn't fit one of the answer choices.

Answer 6

I get why, |x|=6.5 not 7.5 my bad