I have to show that for some constant m:
For all ≠ , show that f(x)=mx+b, where b is some constant. The hint given is to fix and take x=x ; then solve for f(x).
I figured that I should change it to point slope form like this (referring to the hint given):
But I'm not sure if this step is correct or not and how I can turn it into the slope-intercept form? Please help.