Math
Unit 5
8th Grade
Lesson 8 of 15
Graph linear equations using slopeintercept form $${y = mx + b}$$.
In Lesson 8, students are introduced to the slopeintercept form of a linear equation, and they see how it is derived from the proportional equation $${y=mx}$$. They use this form as an efficient way to draw the graph of a linear equation. In Lesson 9, students will encounter equations in standard form, $${ax+by=c}$$, and they will write these equations into slopeintercept form to graph them.
Two linear equations are shown below. Complete the table of values for each one and graph the lines in the same coordinate plane. Then answer the questions that follow.
$$y=2x$$

$$y=2x+3$$

a. $${y=2x}$$ is a proportional relationship represented by a line through the origin (0, 0). In $${y=2x}+3$$, what impact does the “+3” have on the table of values? What impact does it have on the lines in the graph? What transformation is this?
b. What is the $$y$$value of the $$y$$intercept of each line? Where do you see this in the equations?
c. What is the slope of each line? Where do you see this in the equations?
d. Describe the graph of the line $${y=2x}3$$.
For each linear equation below, identify the slope and $$y$$intercept and use them to graph the line.
a. $$y={1\over3} x2$$
b. $$y=3x+4$$
c. $$y=x$$
In each problem below, determine if the linear equation is correctly graphed in the coordinate plane. If it is not, then describe the error and draw the correct graph in the space provided.
The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.
Lesson 7
Lesson 9
Topic A: Comparing Proportional Relationships
Topic B: Slope and Graphing Linear Equations
Topic C: Writing Linear Equations
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