Introduction to Slope Lines

Slope Formula Lesson

By Cathleen Ward

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Slope Formula

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Finding the Slope of a line given a graph or two points.

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You can use any two points on a line to find the slope

​(x₁, y₁) (x₂, y₂)

Multiple Choice

How many points do you need to find the slope of a line?

• 1

• 2

• 3

• 4

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Step by Step:

• 1. Label the Points 1 and 2 (Slope is ALWAYS the same, no matter which point you pick to be the “first” or “second”.)

• 2. Label the X and Y for each point

• 3. Write the values in the slope formula

• 4. Simplify

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Practice

Find the slope of the line that goes through the points (5, 17) and (0,-3).

Step 1: Label the Points

• First Point ------> (X₁, Y₁) = (5, 17)

• Second Point ------> (X₂, Y₂) = (0, -3)

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Step 2: Extract Values

• X₁ = 5 and Y₁ = 17

• X₂ = 0 and Y₂ = -3

​****Minusing a negative give you a positive!

​​Step 3: Plug the values into the slope formula.​

-Remember that Y values go on top and X values go on bottom. ​

-Make note of the MINUS in between each point for the top and bottom​

-Don't mix the first (red) and second (blue) points. 

​ PAY ATTENTION TO YOUR SIGNS!!!!

Step 4: Simplify

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-Solve for m using the Order of Operations (PEMDAS)​

-Make sure that you subtract the numbers correctly. Use a CALCULATOR!

**Remember- subtracting a negative number is the same as adding

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Multiple Choice

Find the slope of the line that goes through the points

(−11,−5) and (1,−12)

• $$-\frac{5}{8}$$  

• $$\frac{16}{11}$$  

• $$\frac{1}{6}$$  

• $$-\frac{7}{12}$$  

Multiple Choice

Find the slope of the line that goes through the points

(−1,−2) and (−3,−4).

• 1

• 2

• 3

• 4