Mr. Alongi Math
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Formulas & graphing

Slope Formula

Slope tells how steep a line is and which direction it moves. It compares the vertical change, called rise, with the horizontal change, called run.

m =y₂ - y₁x₂ - x₁=riserun
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Why should I care?

Slope Is All Around Us

Slope describes how steep something is and how quickly its height changes as it moves forward.

Four examples of slope: a skier descending a mountain, a wheelchair ramp, stairs, and a skateboarder using a ramp
MountainA skier follows a negative slope downhill.Wheelchair rampA safe ramp uses a gentle positive slope.StairsEach step adds the same rise and run.Skate rampThe ramp’s steepness changes the jump.

Read the direction

Four Types of Slope

Positive

Rises from left to right.

Negative

Falls from left to right.

Zero

Horizontal line.

Undefined

Vertical line.

Worked example

Find the Slope Between (1, 2) and (4, 8)

Step 1: Label Both Points

(x₁, y₁) = (1, 2)
(x₂, y₂) = (4, 8)

Keep each point together.

Step 2: Follow the Top

y₂y₁8 − 2 = 6

The change in y is 6.

Step 3: Follow the Bottom

x₂x₁4 − 1 = 3

Use the same subtraction order.

Step 4: Divide and Simplify

Put the change in y over the change in x.

m = 6/3 = 2

Slope calculator

Find Slope From Two Points

Enter two points. The calculator shows every step.

Optional: Enter the two ordered pairs

Entering a value here also changes the matching value in the formula below.

First point (x₁, y₁),
Second point (x₂, y₂),
m =

Step 1: Subtract y₂ - y₁8 - 2 = 6

Step 2: Subtract x₂ - x₁4 - 1 = 3

Step 3: Put the answers into the formulam = 63 = 2

rise = 6run = 3P₁ (1, 2)P₂ (4, 8)

Watch out

Common Mistakes

  • Subtracting x-values on top instead of y-values.
  • Changing the subtraction order halfway through.
  • Calling a vertical line’s slope zero instead of undefined.

Memory tool

Rise Over Run

Vertical change goes on top. Horizontal change goes on the bottom.

Your turn

10-Question Slope Practice

Type the slope, slope type, or coordinate requested.

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