I had to find an equation of a linear function z=c+mx+ny whose graph intersects the xy plane in the line y=2x+2 and contains the point (1,2,2) I got the answer as z=2x-y+2 Now I have to see if the function f which satisfies f(0,0)=0, f(2,0)=3 and f(5,0)=6 linear? and explain it. I have no clue what to do now. Can anyone help me? Thanks!