6)
1- y=x^2-6x+5
2- y-2x=5
by substituting
y=2x+5 into equation 1
2x+5=x^2-6x+5
x^2-8x=0
x(x-8)=0
x=0 and x=8
if x=0,y=2(0)+5=5,(0,5)
if x=8,y=2(8)+5=21,(8,21)
which makes false.
3)
1- y=x^2-2x+2
2- y= 2x-2
by substituting equation 2 into equation 1
2x-2=x^2-2x+2
x^2-4x+4=0
(x-2)^2=0
x=2
if x=2 then y=2(2)-2=4-2=2,(2,2)
so yes it is the only soultion