basically x=something is the axis of symmetry the way to find the axis of symmetry is to convert to vertex form and find h and that's the axis of symmetry
but there's an easier way
for f(x)=ax^2+bx+c the axis of symmetry is x=-b/2a nice hack my teacher taught me
so
f(x)=3x^2+0x+0 axis of symmetry is -0/(3*2), so x=0 is the axis of symmetry for f(x)
g(x)=1x^2-4x+5, axis of symmetry is -(-4)/(2*1)=4/2=2, x=2 is axis of symmetry for g(x)
h(x)=-2x^2+4x+1 axis of symmetry is -4/(2*-2)=-4/-4=1, x=1 is the axis of symmetry for h(x)
0<1<2 axisies f(x)<h(x)<g(x)
order based on their axises of symmetry is f(x), h(x), g(x)