How to gain an inverse function

Set f(x) = y. Then rearrange your equation to find x on it's own as some function of y. If you have a x term on both the top and bottom of a fraction then you will have to multiply the whole equation through by the denominator. Times out any brackets and collect all x terms on one side of the equation with any other terms on the other side. To make it neater you would then replace all the y's with x's to make the inverse of f(x).