slope-intercept equation:
y=mx+b
Where:
m= slope
b=y-intercept
Apply the slope formula:
[tex]m=\frac{(y2-y1)}{(x2-x1)}[/tex]we have the coordinate points:
(x1,y1) = (0,1)
(x2,y2) = (2,9)
Replacing:
[tex]m=\frac{9-1}{2-0}=\frac{8}{2}=4[/tex]So far we have:
y=4x+b
Replace (x,y) by one point from the graph, for example (0,1) and solve for b:
1=4(0)+b
1=b
Final equation:
y= 4x+1
f(x)=4x+1