Tìm x: a) x - (x - 3) - 12 + 4x = 0; b) (x - 4)(x^2 + 4x + 16) - x(x^2 - 6) = -4

Tìm x:
a) x - (x-3) - 12 + 4x = 0
b) (x-4)(x^2 + 4x + 16) - x (x^2 - 6) = -4
c) x^2 - 10x = 11