# Quick inverse question

1. Jul 18, 2011

### Nelo

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

Inverse of g(x) = x/3 -5

2. Relevant equations

3. The attempt at a solution

The inverse of the function

g(x) = x/3 -5
x= y/3 -5
x +5 = y/ 3
3x + 15 = y

Is this correct?

Or is it x+5 /3 ?

2. Jul 18, 2011

### 1MileCrash

If you have a graphic calculator, graph them both, the inverse should be a 90* rotation from the original, since you essentially have the same function with swapped axis.

3. Jul 18, 2011

### Averki

If you want to check to see if the inverse function you found is correct, all you need to do is form a composite function of the original function and its inverse. If the composite function of g(x) and g-1(x) is equal to x, then the inverse you found is correct.

$g[g^{-1}(x)]=(\frac{3x+15}{3})-5=(x+5)-5=x$

Yes, the inverse you found is correct.