Answer
We can use the point-slope form because we have the slope and, with the $x$-intercept that is given, we have a point on the line as well.
Work Step by Step
We can use the point slope form because we have the slope and, with the $x$-intercept that is given, we have a point on the line as well.
The $x$-intercept denotes the value of $x$ when $y = 0$. Therefore, if we know that the $x$-intercept is a value $a$, then we know that the point $(a, 0)$ is on the line and is where the line crosses the x-axis.