4x2-12x-72=0
4x² - 12x - 72 = 0
To reduce the size ofthe numers, divide all numbers by 4:
x² - 3x - 18 = 0
Factor: (x - 6)(x + 3) = 0
To solve: either x - 6 = 0 or x + 3 = 0
x = 6 or x = -3