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Pearson Algebra 1 Common Core, 2011

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Pearson Algebra 1 Common Core, 2011 View details

Cumulative Standards Review

Exercise 28 Page 610

Identify the y-intercept then find another point that lies on the grid.

y=2x-6

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 graph. Let's start with the y-intercept.

Finding the y-intercept

Observe the given graph.

We can see that the function intercepts the y-axis at (0, - 6). This means that the value of b is - 6.

Finding the Slope

To find the slope, we will trace along the line on the given graph until we find a lattice point, which is a point that lies perfectly on the grid lines. In doing so, we will be able to identify the slope m using the rise and run of the graph.

Here we've identified the x-intercept at (3,0) as our other point. Traveling to this point from the y-intercept requires that we move 3 steps horizontally in the positive direction and 6 steps vertically in the positive direction. rise/run=6/3 ⇔ m= 2

Writing the Equation

Now that we have the slope and the y-intercept, we can form our final equation. y= mx+ b y= 2x+( - 6) ⇔ y=2x-6