Tutoring math, you know this skill is essential.  The math tutor provides a quick explanation and example.

The concept of slope is known to all in everyday life.  In math, it is defined as follows:

slope=rise/run=m=(y₂-y₁)/(x₂-x₁)

Indeed, slope is often referred to as m. The rise refers to the change in height; the run, to the change in horizontal position.

This article assumes you understand points on the cartesian plane. If you don’t, see my article here.

Example: Let’s imagine you need the slope of the line pictured here:

We need to realize three facts:

1) Every point is (x,y); x means horizontal position, while y means vertical.

2) “Change” means the final value minus the initial value.

3) Once again, the rise refers to the change in height; the run, to the change in horizontal position.

Now we involve the equation for slope:

m=(y₂-y₁)/(x₂-x₁)

Notice that (x₁,y₁) means “the first point”, while (x₂,y₂) means “the second point.” It’s helpful to label your two points (x₁,y₁) and (x₂,y₂). Next, carefully insert the values in their right places in the equation:

m=(-25-110)/(240-(-100))

Simplifying, we get

m=-135/340=-27/68 or -0.397

Slope is always pictured from left to right. If a line rises to the right, its slope is positive. The line in our example falls to the right; hence, its slope is negative.

The slope of a line has many applications, which I’ll be discussing in future posts:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.