Tìm x: a) (x - 3)(x^2 + 3x + 9) - x(x + 4)(x - 4) = 5

Tìm x
a.(x-3)(x^2+3x+9)-x(x+4)(x-4)=5
b.(x-2)^3-(x+5)(x^2-5x+25)+6x^2=11