# Homework Help: Complex number question

1. Jul 6, 2010

### TheDoorsOfMe

1. The problem statement, all variables and given/known data

Suppose a and b are real numbers, not both 0. Find real numbers c and d, such that

$$\frac{1}{a + bi}$$ = $$c + di$$

2. Relevant equations

I said that:

$$1 = (c + di) (a + bi)$$

$$1 = (ac - bd) + (bc + ad)i$$

so if b = 0 then
$$\frac{1}{a} = c + di$$

The rationale holds for if a = 0. Since this is equal to a real number 1/a can I just say that c and d are real numbers?

2. Jul 6, 2010

### rootX

You need to understand that if
x + yj = a + bj
then
x = a
and
y = b

2)
Multiply left side by a-bj / a-bj