find the vertex and line of symmetry

f(x)=x^2-6x+8
f(x)=3x^2-18x+6
f(x)=4x^2-8x+
f(x)=-2(x+6)^2+6

3 answers

f(x)=x^2-6x+8=2x-6
f(x)=3x^2-18x+6=6x-18
f(x)=4x^2-8x+=8x-8