Equation of a line
The equation of a line in the slope-intercept form is:
y = mx + b
Where m is the slope of the line and b is the y-intercept.
Suppose we know the line passes through points A(x1,y1) and B(x2,y2). The slope can be calculated with the equation:
![\displaystyle m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2023/formulas/mathematics/college/zkw1rebg6qix1w4pvkuol78hb2zfucnx6e.png)
We need to identify two clear points through which the line passes. We select the points (0,-3) and (4,5). Calculate the slope:
![\displaystyle m=(5+3)/(4-0)=(8)/(4)=2](https://img.qammunity.org/2023/formulas/mathematics/college/kvtkdcf7tifrxyacfg55ed668r9jntx3uu.png)
1. The slope is m=2
The y-intercept of the line is the y-coordinate of the point where the line crosses the y-axis.
2. We can see the line crosses the y-axis at the point (0,-3), thus the y-intercept is b=-3.
3. The equation of the line is written as follows:
y = 2x - 3