You can put this solution on YOUR website! If the required interval on x is used, then will be non-negative, and may be either negative or 0. All values of the required interval will make to be positive.
The equation in the expected, given interval becomes
OR
Simplifying those .
Only ONE value of x will use the second equation, x at 5.
The rest of the x values will use the first equation, y=3x-6.