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Big Ideas Math Integrated I, 2016 View details

5. Graphing Linear Equations in Slope-Intercept Form

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Exercise 8 Page 141

Can you think of two different ways to find the slope, given a graph?

Description: Negative
Slope: -4/5

Practice makes perfect

Observing the given graph, we can see that the line passes through the points (0,3) and (5,-1). One way to use a graph to find the slope of a line is to count out the change in x and y.

We can see that as the graph travels from left to right, the rise, or change in y, is -4. Similarly, the run, or change in x, is 5. slope=rise/run ⇔ m=-4/5 We can confirm this answer by using the other method, the Slope Formula. m = y_2-y_1/x_2-x_1 We will use the given points to solve for the slope.

m = y_2-y_1/x_2-x_1

SubstitutePoints

Substitute ( 0,3) & ( 5,-1)

m=-1- 3/5- 0

AddSubTerms

Add and subtract terms

m=-4/5

MoveNegNumToFrac

Put minus sign in front of fraction

m=-4/5

A slope of m=- 45 means that for every 5 steps in the positive horizontal direction, the graph travels 4 steps in the negative vertical direction.