Tìm x, biết: 2x . (3x + 9) - (3x - 1) . (2x + 2) = 16

Tìm x: 
a. 2x (3x + 9) - (3x - 1) (2x + 2) = 16
b. (x + 3)^2 - (2x + 1)^2 = 0