Simplify dfracx2−420x−20\\dfrac{x^2 - 420}{x - 20}dfracx2−420x−20 for xneq20x \\neq 20xneq20
x+21x + 21x+21
x+20x + 20x+20
x−21x - 21x−21
x−20x - 20x−20