Simplify the following:
(x-2) (x+2)-x (x-1)
(x-2) (x+2) = (x) (x) + (x) (2) + (-2) (x) + (-2) (2) = x^2+2 x-2 x-4 = x^2-4:
x^2-4-x (x-1)
-x (x-1) = x-x^2:
x-x^2+x^2-4
Grouping like terms, x^2-x^2+x-4 = x-4+(x^2-x^2):
x-4+(x^2-x^2)
x^2-x^2 = 0:
Answer: | x - 4
