Bell Work:Draw the figure that this net depicts.

Answer:

Lesson 56:The Slope-Intercept Equation of a Line

If the equation of a line is written in slope-intercept form, we can read the slope and y-intercept directly from the equation.

y = (slope)x + (y-intercept)

The slope-intercept equation of the line graphed is y = 3x – 3.

Slope-Intercept Equation:y = mx + b

M represents the slopeB represents the y-intercept

Consider the following graphs and their equations. They both have the same slope equaling 1. The red line though has a y-intercept of zero and the blue line has a y-intercept of 2.

In the following graph, they have the same y-intercept of zero, the first graph has a slope of 2 however, while the second graph has a slope of ½. Which graph has the steeper slope?

The first graphs slope equals zero and has a y-intercept of 2. The second graph’s slope is undefined and every point has an x-coordinate of -4.

A vertical line cannot be expressed in slope-intercept form.

Example:Refer to this equation to answer the questions.

y = 2/3 x – 4 a) Where does the graph of the

equation cross the y-axis?b) Does the line rise to the right

or fall to the right?

Answer:a) y-axis point = -4b) Rises to the right

Practice:Write the equations of the line. At what point does the line cross the y-intercept?

Answer:y = -3x + 4

Practice:Graph the equation using the given slope and y-intercept.

y = 2/3x – 4

Answer:

Practice:Graph the equation using the given slope and y-intercept.

y = -2x – 3

Answer:

HW: Lesson 56 #1-30