Exercise 1 Page 123

Observing the given graph, we can see that the line passes through the points (- 1,2) and (3,- 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 - 3. Similarly, the run, or change in x, is 4. slope=rise/run ⇔ m=- 3/4 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 ( - 1,2) & ( 3,- 1)

m=- 1- 2/3-( - 1)

SubNeg

a-(- b)=a+b

m=- 1-2/3+1

AddSubTerms

Add and subtract terms

m=- 3/4

MoveNegNumToFrac

Put minus sign in front of fraction

m=-3/4

A slope of m=- 34 means that for every 4 steps in the positive horizontal direction, the graph travels 3 steps in the negative vertical direction.