Transcript File - Ms. Hannah Stewart

+ Warm-Up
Find the slope.
1) (4, -6) (4, 3)
2) (5, 3) (-1, 8)
3) (1, 12) (-5, 12)
4) An employee’s wages are directly proportional to the time
worked. If an employee earns $100 for 5 hours, How much will
the employee earn is 18 hours?
5) The amount of money that a magazine pays for an article varies
directly as the number of words in the article. If the magazine
pays $720 for a 1200-word article, how much will the magazine
pay for a 1500-word article?
6) When an electric current is 32 A (amperes), the electromotive
force is 288 V (volts). Find the force when the current is 65 A, if
the force varies directly as the current.
+
Graphing y=mx+b
Unit 3 Day 2
Rise up Run Out
http://www.youtube.com/watch?v=rBAGAdySKSQ
Investigation
of the best vacuum cleaners are only sold door-to-door. The
+ Some
salespeople demonstrate the cleaning ability of the appliance in people’s
homes to encourage them to make the purchase. Michael sells vacuum
cleaners door-to-door. He earns a base salary plus commission on each sale.
His weekly earnings depend on the number of vacuum cleaners he sells as
shown in the table below.
Number of Vacuum Cleaners Sold in a
Week
Weekly Earnings (in Dollars)
2
4
6
8
600
960
1320
1680
A. Identify the independent variable. Identify the dependent variable.
B. Write a NOW-NEXT rule to show how Michael’s weekly earnings E can be
calculated from the number of vacuum cleaners sold in week S.
C. Find the rate of change in earnings as sales increase.
D. Write an equation in intercept form to show weekly earnings over time.
E. What part of Michael’s pay does this figure represent? What is the meaning
of the y-intercept?
F. Use your equation to predict what the weekly earnings are for selling 15
vacuum cleaners
G. Does Michael’s earnings appear to be a linear function of the number of
vacuum cleaners sold.
+ Let’s wrap up what we found...
What is the relationship between a...
NOW-NEXT equation:
Next = Now + 5
Start = 20
And
Explicit equation:
y = 5x + 20
+They mean the same thing! Except the
explicit equation is a short cut!
The explicit equation y=5x + 20 comes from the equation
y=mx+b.
This has a special name:
Slope intercept form
Why do you think it has this name?
+
Slope Intercept Form
y = mx+b
Slope
Y- Intercept
Using Slope and y-Intercept to Graph Lines
y=mx+b
• Given a point on the line, you can use the slope to
get to the "next" point by counting “rise over run".
But how do you find your first point?
• y = mx + b, "b" gives the y-intercept, and "m" is the
slope. We can use this fact to easily graph straight
lines!
LET’S GRAPH!
Y= -2/3x + 4
Y= 2x – 3
+
You can represent linear relationships with a graph, a table of values,
an equation, or a rule stated in words. Here are two relationships.
Give all the other ways to show each relationship.
a)
Day (x)
Height (in
cm)
3
4
4
5
5
6
7
8
b)
Now Lets Write the equation!
1)
2)
3)
4)
Find m
Pick a point and plug in y, x, and m
Solve for b
Rewrite
+
a)
Example 2 - Write the equation of
the line for the following
Day (x)
Height (in
cm)
5
9
7
11
9
13
b) (-1,2) and (4,5)
+
Your Turn – Write an equation of a
line for the following.
1.
(2, 4) and (5, 6)
2.
M= -2 and b = 4
3.
With a slope of 2 and through
the point (1,3)
4.
(-3,5) and (-1, 6)
+
3-2 Classwork
y = mx + b

Day 2 Classwork

Graphing Worksheet

Due at the end of class

Match the equations at the
back with the graphs!

Homework if you do not finish