You can
put this solution on YOUR website!Any value I pick for

except

will give me a value for

which is
greater than

by some amount, so
(4, -1) is a minimum vertex.
The x-intercept is where

The x-intercepts are (5,0) and (3,0)
The y-intercept is where

The y-intercept is at (0,15)
Here's the plot: