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McGraw Hill Integrated I, 2012

MH

McGraw Hill Integrated I, 2012 View details

Mid-Chapter Quiz

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Exercise 1 Page 246

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

y=3x+7

Practice makes perfect

Equations written in Slope-Intercept Form follow a specific format. y= mx+ b In this form, m is the slope of the line and b is the y-intercept. We need to use the graph to identify these values. 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, 7). This means that the value of b is 7.

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 (- 2,1) as our other point. Traveling to this point from the y-intercept requires that we move 2 steps horizontally in the negative direction and 6 steps vertically in the negative direction. rise/run=- 6/- 2 ⇔ m= 3

Writing the Equation

Now that we have the slope and the y-intercept, we can form our final equation. y= mx+ b y= 3x+ 7

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Exercises p.246