# Help with equation

1. Dec 13, 2006

### Alec

1. The problem statement, all variables and given/known data
Decide the real value of x making Re(10 / x+4i) = 1

2. Relevant equations
I know that you can extend the equation with x-4i.

3. The attempt at a solution
But then the equation looks like this: (10x-40i) / (x^2 + 16) = 1
I don't know how to get rid of the -40i to make it in to a real equation.

Any help would be valuable!

2. Dec 13, 2006

### HallsofIvy

Staff Emeritus
$$\frac{10x-40i}{x^2+ 16}= \frac{10x}{x^2+16}-i\frac{40}{x^2+ 16}$$

3. Dec 13, 2006

### daveb

It says the real part of (10x - 40i)/(x^2 + 16) = 10x/(x^2+16) - 40i/(x^+16). Take the real part of that and set it equal to 1, and solve for x.