You can put this solution on YOUR website! (4x^2 - 25) / (2x^2 + 3x - 20)
The denominator cannot be zero so we need to solve:
2x^2 + 3x - 20 = 0
(2x-5)*(x+4) = 0
The denominator becomes zero when either:
2x-5 = 0 or
x+4 = 0
Solve each of these for x.