Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Writing and Graphing Linear Equations
Slope formula:
Slope­intercept form:
Standard form:
Point­slope form:
Slope of a Horizontal line:
Equation of a Horizontal line:
Slope of a Vertical line:
Equation of a Vertical line:
Definitions
Writing Equations of Lines
You always need slope and one point to write the equation of a line, except for the equation of a vertical line.
Write an equation in slope­intercept form for the line that has the indicated slope and passes through the given point.
Example 1) m =3, (1, ­3)
Method 1: Point­slope form
Method 2: Slope­intercept form
Slope and One Point
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Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Example 2) m = ­3/4, (2, 1)
Slope and One Point
Write an equation in slope­intercept form for the line containing the given points.
FIRST, find the slope. THEN, choose one of the two points to set up the equation.
Example:
3. (1, ­5) and (2, ­3) Given Two Points
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Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Write the equation of the line that passes through the given points:
4. (2, 4) and (­4, 1)
5. x­intercept of ­2 and y­intercept of 2
Given Two Points
The slopes of parallel lines are always _________________ .
Example: Write the equation of a line that: 6) passes through (4, 5) and is parallel to y = 3/2 x + 6
Parallel/Perp Slope
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Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Warm Up
Write the slope­intercept form of the equation for the line that:
1. passes through (­3, ­1) and has slope of 3/4. 2. passes through (­1/2, 1/2) and (3/2, 5/2). 3. Write the equation of a line that passes through (2, 1) and is parallel to y = 3/2 x + 7.
Warm Up
HW Answers
1. y = ­8x + 8 2 . y = 3/4 x + 65/4
3. y = ­1/2 x + 1/3 4. x = 1
5. y = 1/2 x ­ 11/2 6. x = 4
7. y = x ­ 4 8. y = 3/2 x + 11/2
9. x = 7 10. y = ­x + 3
11. y = 5/4 x ­ 5 12. y = ­8x + 16/3
HW Answers
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Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Sep 2­6:40 PM
The slopes of perpendicular lines are always _________________________ .
Example: Write the equation of a line that: 7) passes through (6, ­ 4) and is perpendicular to y = ­3/4 x + 2
Parallel/Perp Slope
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Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Example: Write the equation of a line that: 8) passes through (­1, ­ 3) and is perpendicular to 2x + 5y = 15
Parallel/Perp Slope
Equations of Horizontal and Vertical Lines
horizontal line vertical line
y = # x = #
Horizontal is parallel to horizontal.
Vertical is parallel to vertical.
Horizontal is perpendicular to vertical.
Examples: Write the equation of a line that 9. passes through (3,­4) and is perpendicular to x = 7
10. passes through (4, ­10) and is parallel to x = ­5
Horizontal/Vert Lines
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Day 3 Part 2 Writing Equations of Lines.notebook
August 17, 2016
Examples: Write the equation of a line that:
11. is horizontal and passes through (­3, 1)
12. is vertical and passes through (­2, 7)
13. that passes through (4, ­5) and (4, 7)
Horizontal/Vert Lines
PRACTICE
1. Write the equation of a line that passes through (5, ­3) and has
slope m = 4. 2. Write the equation of a line that passes through (1, 3) and is parallel to 2x ­ y = 1
3. Write the equation of a line that passes through (­4, 7) and is perpendicular to y = 4/5 x ­ 1.
4. Write the equation of the vertical line that passes through (2, ­7).
Practice
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Attachments
Practice 2.4 Writing Linear Equations 2.doc
Worksheet Write Linear Equations.doc
Alg 2 CP2 5th­6th Seating Chart.doc