The equations of the line are
and
.
How to determine the equation of a line
In this problem we must determine two line equations based on information available on graph. Lines are modelled after the following expression:
y = m · x + b
Where:
- x - Independent variable.
- y - Dependent variable.
- m - Slope
- b - Intercept
Slope can be found by means of secant line formula:

Where:
- Δx - Change in independent variable.
- Δy - Change in dependent variable.
And intercept of the line is the point that is on y-axis.
Now we proceed to determine the equation of the line:
Case 1:
Slope:


Intercept:
b = y - m · x
b = 1 - m · 0
b = 1
The equation of the line is
.
Case 2:
Slope:

m = - 7
Intercept:
b = y - m · x
b = 2 - m · 0
b = 2
The equation of the line is
.