Question

if the complex number x=3+bi and lxl^2=13 which is a possible value of b?
A:2
B:4
C:9
D:10

Answer 1

|x| is called the modulus of a complex number.

If x = a+bi
\(|x| = \sqrt{a^2+b^2}\)

so what will be |x|^2 when x = 3+bi ?

Answer 2

i have no clue lol

Answer 3

so,
when x = 3+bi
\(|x|^2 = 3^2 + b^2\)

now this is given to be 13

so
3^2+b^2 = 13

can you find 2 possible values of b from this?

Answer 4

b=2?

Answer 5

very good! :)
correct.

Answer 6

thanks for the help