Gradient = [tex]\frac{y_{1}-y_{2}}{x_{1}-x_{2}}[/tex]
[tex]\frac{5-1}{2-1} \\\frac{4}{1}[/tex]
This means the gradient is 4x.
The y intercept is where the line crosses the y axis. We can see this is at -3.
Rule: y = 4x -3
Substitute your values to check if it's right.
y = 4x -3
5 = 4(2) - 3
5 = 8 - 3
5 = 5
1 = 4(1) - 3
1 = 4 - 3
1 = 1
