3б
x²-4x-12=0
x1+x2=4 U x1*x2=-12⇒x1=-2 U x2=6
(x-5)²/(x+2)(x-6)≥0
+ _ _ +
------------(-2)------------[5]-----------------(6)--------------
x∈(-∞;-2) U (6;∞) U {5}
6
x³(x-2)+x²(x-2)-x(x-2)+2(x-2)=0
(x-2)(x³+x²-x+2)=0
(x-2)[x²(x+2)-x(x+2)+(x+2)]=0
(x-2)(x+2)(x²-x+1)=0
x-2=0⇒x=2
x+2=0⇒x=-2
x²-x+1=0
D=1-4=-3<0 нет решения<br>