Module 6.1

Slope-Intercept Form

How can you represent a linear function in a way that reveals its slope and y-intercept?

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In this module we’re working with Slope-Intercept (SI) Form.

We’ll do 3 things:

1) Given the Slope of a line and one point on that line, we’ll determine the equation of the line (in SI Form).

2) Given 2 points on a line, we’ll determine the equation of the line (in SI Form).

3) Given the equation of a line (in SI form), we’ll graph the line.

1) Given the Slope of a line and one point on that line, we’ll determine the equation of the line (in SI Form).

Two Steps:1) Find the Y-Intercept2) Write the equation.

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2) Given 2 points on a line, we’ll determine the equation of the line (in SI Form).Three Steps:

1) Fine the slope2) Find the Y-Intercept3) Write the equation.

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3) Given the equation of a line (in SI form), we’ll graph the line.Four Steps:

1) Convert the equation to SI form, if necessary2) Plot the Y-Intercept3) Plot a 2nd point, using the slope4) Draw a line between them, with arrows.

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What is the advantage of graphing from slope-intercept form? The intercept is one point on the line and a second point can be found easily by using the slope.

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A figure skating school offers introductory lessons at $25 per session. There is also a registration fee of $30. Write a linear equation in slope-intercept form that represents the situation. You want to take at least 6 lessons. Can you pay for those lessons using a $200 gift certificate? If so, how much money, if any, will be left on the gift certificate? If not, explain why not.

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How does the value of b indicate whether the graph is above or below the origin where it intersects the y-axis? If b is positive, the y-intercept is positive and the graph intersects the y-axis above the origin. If b is negative, the y-intercept is negative and the graph intersects the y-axis below the origin.

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