Big Ideas Math: Modeling Real Life, Grade 8
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6. Writing Equations in Slope-Intercept Form
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Exercise 1 Page 174

First, use the given points to calculate the slope. Then, identify the y-intercept.

y=2x+2

Practice makes perfect
Equations written in slope-intercept form follow a specific format. y= mx+ b In this form, m is the slope and b is the y-intercept. We need to identify these values using the given graph.
Let's start by substituting the points given on the graph into the Slope Formula and calculating m.
m = y_2-y_1/x_2-x_1
m=4- 2/1- 0
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Simplify right-hand side
m=2/1
m= 2
We calculated that the slope of the given equation is 2. Now, let's calculate the y-intercept and then write the equation in slope-intercepted form.

y-intercept

The y-intercept is the y-value where the line crosses the y-axis.

We can see that the function intercepts the y-axis at (0, 2). This means that the value of b is 2.

Writing the Equation

Now that we have the slope and the y-intercept, we can write our final equation. y= 2x+ 2