N
ngoc_2000


a. (x+3)^2-(x-3)^2 - 12x
b. x(x-1)(x+1)-(x-1)(x^2-x+1)
c. 3x(x-1)^2-2x(x-3)(x+3)+4x(x-4)
thanks các bạn@};-
b. x(x-1)(x+1)-(x-1)(x^2-x+1)
c. 3x(x-1)^2-2x(x-3)(x+3)+4x(x-4)
thanks các bạn@};-