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McGraw Hill Glencoe Algebra 2, 2012

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McGraw Hill Glencoe Algebra 2, 2012 View details

Standardized Test Practice

Exercise 15 Page 381

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

Slope: 1/2
y-intercept: 3

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 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 (0,3). This means that the value of b is 3.

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 (-6,0) as our other point. Traveling to this point from the y-intercept requires that we move 6 steps horizontally in the negative direction and 3 steps vertically in the negative direction. rise/run=-3/-6 ⇔ m= 1/2 Finally, the slope of the equation of the line graphed is equal to 12 and the y-intercept is 3

Subchapter links

Exercises p.380-381