Transcript The y- intercept is

Do Now 10/26/09
Take out HW from Friday.
–Text p. 219, #6 & 8, 16-32 even, 38
Copy HW in your planner.
–Text p. 229, #8-22 even #28-40 even, 46
–Quiz Sections 4.1 – 4.3 Wednesday
In your notebook, define the word INTERCEPT
in your own words. Use the word in a sentence
that is NOT math related.
Homework
Text p. 219, #6 & 8, 16-32 even, 38
6) not a solution
8) not a solution
16-22) graphs on overhead
24) A
26) y ≥ -2
28) y = 4
30) -5 ≤ y ≤ 3
32) The equations are the same, each term in the first
equation was multiplied by 2 to get the second equation.
3x – 3y = 9.
38) a. $190; substitute 3 in for f and solve.
b. 13 1/3 yd; substitute 500 in for C and solve.
Linear FunctionThe equation Ax + By = C
represents a linear function as long as
B = 0.
Graph a Function
Graph the function y = – 3x + 1 with domain x ≤ 0.
Then identify the range of the function.
SOLUTION
STEP 1
Make a table.
x
0
–1
–2
–3
–4
y
1
4
7
10
13
STEP 2
Plot the points.
STEP 3
Connect the points with a ray
because the domain is restricted.
STEP 4
Identify the range. From the graph, you can see that all points have a
y-coordinate of 1 or more, so the range of the function is y ≥ 1.
Objective
SWBAT graph a linear equation
using intercepts
Section 4.3 “Graph Using Intercepts”
x-interceptthe x-coordinate of the point where
the graph crosses the x-axis
To find the x-intercept, solve for ‘x’ when ‘y = 0.’
Find the x-intercept of the graph
2x + 7y = 28
2x + 7(0)= 28
2x = 28
x = 14
2x + 7y = 28.
Section 4.3 “Graph Using Intercepts”
y-interceptthe y-coordinate of the point where
the graph crosses the y-axis
To find the y-intercept, solve for ‘y’ when ‘x = 0.’
Find the y-intercept of the graph
2x + 7y = 28
2(0)+ 7y= 28
7y = 28
y=4
2x + 7y = 28.
Use Intercepts to Graph an Equation
Graph the equation
Find the x-intercept
x + 2y = 4.
Find the y-intercept
x + 2y = 4
x + 2y = 4
x + 2(0) = 4
0 + 2y = 4
x = 4  x-intercept
Plot points. The x-intercept is 4, so plot
the point (4, 0). The y- intercept is 2, so
plot the point (0, 2). Draw a line through
the points.
y = 2  y-intercept
Use Intercepts to Graph an Equation
Graph the equation
Find the x-intercept
6x + 7y = 42.
Find the y-intercept
6x + 7y = 42
6x + 7y = 42
6x + 7(0)=42
6(0) + 7y = 42
x = 7  x-intercept
Plot points. The x-intercept is 7, so plot the
point (7, 0). The y- intercept is 6, so plot the
point (0, 6). Draw a line through the points.
y = 6  y-intercept
Use a Graph to Find Intercepts
The graph crosses the x-axis at (2, 0). The x-intercept is 2.
The graph crosses the y-axis at (0, – 1). The y-intercept is – 1.
Use a Graph to Find Intercepts
The graph crosses the x-axis at (–4, 0). The x-intercept is –4.
The graph crosses the y-axis at (0, 2). The y-intercept is 2.
Problem Solving Using Linear Equations
You are working at a local park and are in charge of
renting skateboards and bikes. You rent bikes for $8.00
a day and skateboards for $4.00 a day. At the end of the
day you have made a profit of $1200.
Write an algebraic
equation to represent
the situation. Use ‘x’
for skateboards and ‘y’
for bikes.
4x + 8y = 1200
bikes
Using the graph,
make a table of
values to show
the different
combinations of
rentals that
could have
resulted in a
$1200 profit.
50
50
100
150
200
skateboards
250
300
24
Homework
Text p. 229, #8-22 even #28-40 even, 46