How to find the slope of a line

How to find the slope of a line?

 Read,6 minutes

Slope measures the steepness and direction of a line. It compares vertical change to horizontal change, often described as rise over run.

For two points \((x_1,y_1)\) and \((x_2,y_2)\), use \(m = \frac{y_2 - y_1}{x_2 - x_1}\). When a line is written as \(y = mx + b\), the coefficient \(m\) is the slope.

A horizontal line has slope \(0\). A vertical line has undefined slope because its run is \(0\).

Finding Slope

Think of this lesson as more than a rule to memorize. Finding Slope is about rate of change, slope, intercepts, and coordinate patterns. A strong student does not rush to the first formula on the page; they pause, identify the structure of the problem, and then choose the tool that matches that structure. That pause is what prevents most mistakes.

Slope measures rate of change: \(m=\frac{y_2-y_1}{x_2-x_1}\). Read it as change in \(y\) divided by change in \(x\).

Here is the teacher way to approach the topic. First, read the problem slowly and underline the information that is actually given. Next, name the target: are you finding a value, simplifying an expression, comparing two quantities, solving for a variable, or interpreting a graph? Once the target is clear, the calculation becomes much less mysterious because every step has a job.

  • Identify the input value or expression.
  • Substitute carefully using parentheses.
  • Simplify one operation at a time.
  • Check domain restrictions such as zero denominators or even roots.

A helpful habit is to say what each number represents before using it. For example, if a number is a denominator, a radius, a slope, a common difference, or a coefficient, it should not be treated like an ordinary loose number. Its role tells you where it belongs in the formula. This is especially important on ACT-style questions because many wrong answer choices come from using the right numbers in the wrong places.

Another good habit is to keep the work organized vertically. Write one clean line for substitution, one line for simplifying, and one line for the final answer. If the problem has units, keep the units attached. If the problem has signs, exponents, or parentheses, copy them carefully from one line to the next. Most errors in this topic are not caused by a hard idea; they are caused by dropping a negative sign, combining unlike terms, using the wrong denominator, or skipping a check.

When you finish, ask a quick reasonableness question. Should the answer be positive or negative? Should it be larger or smaller than the original number? Does it fit the graph, table, shape, or equation? Can you plug it back into the original problem? This final check turns the lesson from a procedure into understanding.

On a test, the goal is not to write the longest solution. The goal is to write enough clear work that you can see the structure, avoid traps, and recover quickly if one line goes wrong. Practice the examples below with that mindset: identify the type of problem, choose the matching rule, show the substitution, simplify carefully, and check the answer before moving on.

Free printable Worksheets

Exercises for Finding Slope

1) Find the slope through \((1, 2)\) and \((5, 10)\)

2) Find the slope through \((-3, 4)\) and \((1, -4)\)

3) Find the slope of \(y = 7x - 3\)

4) Find the slope of \(2y = -6x + 8\)

5) Find the slope through \((0, -5)\) and \((4, 3)\)

6) Find the slope of \(x = -2\)

7) Find the slope of \(y = 9\)

8) Find the slope through \((-2, -1)\) and \((3, 14)\)

9) Find the slope of \(4x + 2y = 10\)

10) Find the slope through \((6, 1)\) and \((2, 1)\)

11) Find the slope through \((4, -7)\) and \((4, 5)\)

12) Find the slope of \(3x - y = 12\)

13) Find the slope through \((-5, 8)\) and \((1, 2)\)

14) Find the slope of \(y = -\frac{2}{3}x + 6\)

15) Find the slope through \((2, -3)\) and \((8, 0)\)

16) Find the slope of \(5y = 15x - 20\)

17) Find the slope through \((-1, 6)\) and \((2, 0)\)

18) Find the slope of \(6x + 3y = -9\)

19) Find the slope through \((7, -2)\) and \((-1, 2)\)

20) Find the slope of \(y + 4 = 0\)

 
1)

Find the slope through \((1, 2)\) and \((5, 10)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{10 - 2}{5 - 1} = \frac{8}{4} = 2\)

2)

Find the slope through \((-3, 4)\) and \((1, -4)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{-4 - 4}{1 - (-3)} = \frac{-8}{4} = -2\)

3)

Find the slope of \(y = 7x - 3\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = 7\)

4)

Find the slope of \(2y = -6x + 8\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

Divide by \(2\): \(y = -3x + 4\), so \(m = -3\).

5)

Find the slope through \((0, -5)\) and \((4, 3)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{3 - (-5)}{4 - 0} = 2\)

6)

Find the slope of \(x = -2\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

This vertical line has undefined slope.

7)

Find the slope of \(y = 9\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

This horizontal line has slope \(0\).

8)

Find the slope through \((-2, -1)\) and \((3, 14)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{14 - (-1)}{3 - (-2)} = 3\)

9)

Find the slope of \(4x + 2y = 10\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

Solve: \(2y = -4x + 10\), \(y = -2x + 5\), so \(m=-2\).

10)

Find the slope through \((6, 1)\) and \((2, 1)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{1 - 1}{2 - 6} = 0\)

11)

Find the slope through \((4, -7)\) and \((4, 5)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{5 - (-7)}{4 - 4} = \frac{12}{0}\), so the slope is undefined.

12)

Find the slope of \(3x - y = 12\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

Solve: \(-y = -3x + 12\), \(y = 3x - 12\), so \(m=3\).

13)

Find the slope through \((-5, 8)\) and \((1, 2)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{2 - 8}{1 - (-5)} = -1\)

14)

Find the slope of \(y = -\frac{2}{3}x + 6\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

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

15)

Find the slope through \((2, -3)\) and \((8, 0)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{0 - (-3)}{8 - 2} = \frac{1}{2}\)

16)

Find the slope of \(5y = 15x - 20\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

Divide by \(5\): \(y = 3x - 4\), so \(m=3\).

17)

Find the slope through \((-1, 6)\) and \((2, 0)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{0 - 6}{2 - (-1)} = -2\)

18)

Find the slope of \(6x + 3y = -9\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

Solve: \(3y = -6x - 9\), \(y=-2x-3\), so \(m=-2\).

19)

Find the slope through \((7, -2)\) and \((-1, 2)\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

\(m = \frac{2 - (-2)}{-1 - 7} = -\frac{1}{2}\)

20)

Find the slope of \(y + 4 = 0\)

Use \(m = \frac{y_2 - y_1}{x_2 - x_1}\) for two points, or rewrite the equation in \(y = mx + b\) form.

Rewrite as \(y=-4\). This is horizontal, so \(m=0\).

Finding Slope Practice Quiz