3x+12=0⇒3x=-12⇒x=-4
x²-2x=0
x(x-2)=0
x=0 U x=2
_ + _ +
----------------(-4)-------------(0)----------------(2)---------------------------
x∈(-∞;-4) U (0;2)
.......................................................
(X+2)^2==x^2+4x+4
(3y-X)^2=9y^2-6xy+x^2