so you have to find the equation of the line of both then find the value of k
so f(x) points are (0,1) and (2,6)
hopefully you know how to find a equation of a line between two points
if not i can explain after, most people just want the answer here anyways
y=5/2x+1
g(x) points (0,-1) and (2,4)
y=3x-2
g(x) = f(x) + k
5/2x-1= 5/2x+1 + k
so k = -2
hope this helps
