Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
2. Slope of a Line
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Exercise 1 Page 149

Given a graph, can you think of two different ways to find the slope.

-1/5

Practice makes perfect

Observing the given graph, we can see that the line passes through the points (-2,3) and (3,2). We can use a graph to find the slope of a line. Let's take a look at the change in x and y between the given points.

We can see that as the line falls from left to right. Therefore, the slope is negative. The rise, or change in y, is -1. Similarly, the run, or change in x, is 5. Now we are ready to find the slope m. m=rise/run ⇔ m=-1/5=- 1/5 We can confirm this answer by using the formula. m = y_2-y_1/x_2-x_1 We can use the given points to solve for the slope.
m = y_2-y_1/x_2-x_1
m=2- 3/3-( -2)
m=2-3/3+2
m=-1/5
m=-1/5
We got the same number as before. We can be sure the slope of the line is - 15.