Tìm x biết: a) (x - 3)(x^2+ 3x + 9) + x(x + 2)(2 - x) = 1; b) (x +2 )^2 - (x - 2)(x + 2) = 0; c) (x - 3)^3 - (x - 3)(x^2 + 3x + 9) + 9(x + 1)^2 = 15

Tìm x biết:
a) (x-3)(x^2+3x+9)+ x(x+2)(2-x)=1
b) (x+2)^2-(x-2)(x+2) =0
c) (x-3)^3 -(x-3)(x^2+3x+9)+ 9(x+1)^2= 15
d) 4x^2= 81
e) (x+2)^2 -x+4=0
f) (x+2)^2= (2x-1)^2