We can solve examples of the slope of a line using the slope formula. This formula is derived by dividing the change in y by change in x. The slope defines the inclination of the line. A positive slope indicates that the line grows from left to right, whereas a negative slope indicates that the line decreases from left to right.

Here, we will review the slope formula and use it to solve some practice problems.

GEOMETRY
formula for the slope of a line using two points

Relevant for

Learning to determine the slope of a line with examples.

See examples

GEOMETRY
formula for the slope of a line using two points

Relevant for

Learning to determine the slope of a line with examples.

See examples

Review of the formula for the slope of a line

The formula for the slope of a line is obtained by dividing the change in y of two points that are located on the line by the change in x of the points. Therefore, if we have two points A = (x_{1}, y_{1}) and B = (x_{2}, y_{2}) that are located on the same line, the slope formula is:

Formula for the slope

m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}

Slope of a line – Examples with answers

The following examples are solved using the formula for the slope of a line. Try to solve the problems yourself before looking at the solution.

EXAMPLE 1

What is the slope of a line that has the points (2, 1) and (4, 5)?

We have the following coordinates:

  • (x_{1}, y_{1})=(2, 1)
  • (x_{2}, y_{2})=(4, 5)

We use the slope formula with the given coordinates:

m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}

m=\frac{5-1}{4-2}

m=\frac{4}{2}

m=2

The slope of the line is 2.

EXAMPLE 2

We have the points (3, 2) and (6, 3) that are part of a line. What is the slope?

We have the following values:

  • (x_{1}, y_{1})=(3, 2)
  • (x_{2}, y_{2})=(6, 3)

Using the slope formula with these values, we have:

m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}

m=\frac{3-2}{6-3}

m=\frac{1}{3}

The slope of the line is \frac{1}{3}.

EXAMPLE 3

Determine the slope of a line containing the points (-1, 3) and (6, -4).

We write the values as follows:

  • (x_{1}, y_{1})=(-1, 3)
  • (x_{2}, y_{2})=(6, -4)

Using these values in the formula, we have:

m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}

m=\frac{-4-3}{6-(-1)}

m=\frac{-7}{7}

m=-1

The slope of the line is -1.

EXAMPLE 4

If a line has the points (-2, 1) and (6, -3), what is its slope?

We have the coordinates:

  • (x_{1}, y_{1})=(-2, 1)
  • (x_{2}, y_{2})=(6, -3)

We apply the slope formula with the given coordinates:

m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}

m=\frac{-3-1}{6-(-2)}

m=\frac{-4}{8}

m=-\frac{1}{2}

The slope of the line is -\frac{1}{2}.


Slope of a line – Practice problems

The following problems can be solved by applying what you have learned about the slope of a line. In case you need help with this, you can look at the solved examples above.

Determine the slope of the line that contains the points (4, 2) and (9, 4).

Choose an answer






What is the slope of a line that passes through the points (-3, 1) and (2, 4)?

Choose an answer






If a line has the points (-3, -2) and (2, -8), what is the slope?

Choose an answer






What is the slope of a line that contains the points (-3, -2) and (1, -10)?

Choose an answer







See also

Interested in learning more about distance, midpoint, and slope on the plane? Take a look at these pages:

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