# Math Help - inverse function

1. ## inverse function

how do i find the inverse function of : $y = x + \frac{1}{x}$

this one is giving me trouble.

2. Originally Posted by tsal15
how do i find the inverse function of : $y = x + \frac{1}{x}$

this one is giving me trouble.
So you want to get x with respect to y.

$xy=x^2+1$

$x^2-xy+1=0$

solve the quadratic

3. Originally Posted by Moo
So you want to get x with respect to y.

$xy=x^2+1$

$x^2-xy+1=0$

solve the quadratic
So, using the quadratic equation, i got $y = \frac{x \pm \sqrt{x^2 -4}}{2}$ as the inverse function. Correct?

4. ## switch x and y

yes you are correct