Graphs of Linear Equations in Two Variables
Videos to help Grade 8 students learn some facts about graphs of linear equations in two variables.
Plans and Worksheets for Grade 8
Plans and Worksheets for all Grades
Lessons for Grade 8
Common Core For Grade 8
New York State Common Core Math Module 4, Grade 8, Lesson 21
Lesson 21 Student Outcomes
• Students write the equation of a line given two points or the slope and a point on the line.
• Students know the traditional forms of the slope formula and slope-intercept equation.
Lesson 21 Student Summary
The point-slope form of a linear equation is given by m(x2
) = y2
Given a known (x, y), then the equation is written as m(x - x1
) = y - y1
The following is slope-intercept form of a line: y = mx + b
In this equation, m is slope and b is the y-intercept.
To write the equation of a line you must have two points, one point and slope, or a graph of the line.
Lesson 21 Opening Exercise
Examples 1 - 4
Let a line l be given in the coordinate plane. What linear equation is the graph of line?
1. Write the equation for the line l shown in the graph.
2. Write the equation for the line l shown in the graph.
3. Determine the equation of the line that goes through points (-4, 5) and (2, 3).
4. Write the equation for the line l shown in the graph.
5. A line goes through the point (8, 3) and has slope m = 4. Write the equation that represents the line.