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Lesson Plans and Worksheets for Grade 8

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Common Core For Grade 8

### New York State Common Core Math Grade 8, Module 4, Lesson 21

• 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(x_{2} - x_{1}) = y_{2} - y_{1}

Given a known (x, y), then the equation is written as m(x - x_{1}) = y - y_{1}

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?

Exercises 1–5

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.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

Lesson Plans and Worksheets for Grade 8

Lesson Plans and Worksheets for all Grades

More Lessons for Grade 8

Common Core For Grade 8

Examples, solutions, worksheets, and videos to help Grade 8 students learn some facts about graphs of linear equations in two variables.

Download Worksheets for Grade 8, Module 4, 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(x

Given a known (x, y), then the equation is written as m(x - x

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?

Exercises 1–5

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.

Rotate to landscape screen format on a mobile phone or small tablet to use the **Mathway** widget, a free math problem solver that **answers your questions with step-by-step explanations**.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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