y=-x+6
y=x^2-5x+10 -> metoda substitutiei.
-x+6=x^2-5x+10
-x+6-x^2+5x-10=0
4x-4-x^2=0
-(x^2-4x+4)=0
-(x-2)^2=0
(x-2)^2=0
x-2=0
x=2
y=-2+6
y=4
