Exercise 10 Page 127

We want to find the slope of the line by using the graph. Observing the given graph, we can see that the line passes through the points (- 3,6) and (- 1,2). One way to use a graph to find the slope of a line is to count the change in the x -coordinates and the change in the y-coordinates.

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 2. slope=rise/run ⇔ slope=- 4/2=- 2 We can confirm this answer by using the Slope Formula. slope = y_2 - y_1/x_2 - x_1 We will use the given points to find the slope.

slope = y_2 - y_1/x_2 - x_1

SubstitutePoints

Substitute ( - 3, 6) & ( - 1, 2)

slope=2- 6/- 1-( - 3)

▼

Simplify right-hand side

SubNeg

a-(- b)=a+b

slope = 2-6/- 1 + 3

AddSubTerms

Add and subtract terms

slope=- 4/2

MoveNegNumToFrac

Put minus sign in front of fraction

slope=-4/2

CalcQuot

Calculate quotient

slope = - 2

We obtained the same number as before. We can be sure the slope is - 2.