Tìm x, biết: 2x(3 - x) + 2x^2 = 12; x(x - 2) - x + 2 = 0

a)2x(3-x)+2x^2=12
b)x(x-2)-x+2=0
c)x^3-0,25x=0
d)x^2+4x+3=0