For what values of xxx is x2−x−12x2+x−20\dfrac{x^2 - x - 12}{x^2 + x - 20}x2+x−20x2−x−12 undefined?
x=4x = 4x=4 or x=−5x = -5x=−5
x=3x = 3x=3 or x=−4x = -4x=−4
x=0x = 0x=0
x=−4x = -4x=−4 or x=5x = 5x=5