Chapter 4.7 Point­Slope Form.notebook
November 02, 2016
Bellwork:
Solve
1)
Homework Questions???
2)
Write the equation of the line in slope­intercept form:
3) slope: ­3, (0, 4) is on the line
Nov 3­9:47 AM
Nov 3­9:54 AM
What are the two forms of a linear function we have already learned?
Chapter 4.7 Point­Slope Form
Graph a line and write a linear equation using point­slope form. Write a linear equation given two points.
Standard Form
Slope­Intercept Form
Ax + By = C
y = mx + b
What information do the different forms give us?
Nov 3­9:55 AM
The last form of a linear equation is the Point­Slope Form:
Point­Slope form of a line is useful to write an equation when given the slope and any point on the line. This form comes from the slope formula.
Nov 3­9:56 AM
Point­Slope Form
The line with a slope m that contains the point (x1, y1) can be described by the equation
y ­ y1 = m(x ­ x1)
Let the slope of a line be 4 and contain the point (1, 3).
Nov 3­10:01 AM
Nov 3­10:05 AM
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Chapter 4.7 Point­Slope Form.notebook
Write the equation of a line in point­slope form.
November 02, 2016
We can also use point­slope form to write an equation in slope­
intercept form.
1) slope = 1/6; (5, 1)
To write an equation in slope­intercept form:
slope= 3, (1, 4) is on the line.
Substitute values into point slope form
2) slope = ¾; (­1, ­4)
Simplify expression by distributing
Solve for y
Nov 3­10:07 AM
Write the equation that describes each line in slope­intercept form.
Nov 3­10:10 AM
Writing an equation when given two points:
Write an equation of the line in slope intercept form that contains the point (2, ­3) and (4, 1).
3) slope = ­3; (4, 5)
Step 1: Find the slope
Step 2: Pick one point and substitute into point­slope form
Step 3: Distribute
Step 4: Solve for y
Nov 3­10:15 AM
Write an equation of the line in slope intercept form that has an x­intercept = 1/4 and y­intercept = 1.
Step 1: Find the slope
Nov 3­10:16 AM
Write the equation of each line described in slope intercept form:
4) (1, 3) and (­3, 9)
Step 2: Pick one point and substitute into point­slope form
Step 3: Distribute
Step 4: Solve for y
Nov 3­10:18 AM
Nov 3­10:19 AM
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Chapter 4.7 Point­Slope Form.notebook
5) The points (10, ­3) and (5, ­2) are on a line. Find the intercepts.
November 02, 2016
6) The points (1, ­2) and (3, 10) are on a line. Find the intercepts.
Step 1: Find the slope
Step 1: Find the slope
Step 2: Write the equation in slope intercept form
Step 2: Write the equation in slope intercept form
Step 3: Find the intercepts
Step 3: Find the intercepts
Nov 3­12:51 PM
7) The cost to stain a deck is a linear function of the deck's area. The costs to stain 100, 250, and 400 square feet are shown in the table. Write an equation in slope­intercept form that represents the function. Then find the cost to stain a deck whose area is 75 square feet.
2
Area (ft )
100
250
400
Cost ($)
150
337.50
525
Nov 3­12:54 PM
Nov 3­12:53 PM
Homework
P. 279­282 #1­39(odds) 49, 53
skip #5, 21
Nov 3­12:57 PM
Oct 20­3:48 PM
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