Download Y intercept

Thursday Warm Up
.
Summer Jobs! You have 2 summer jobs. You work 20 hours per week at the
first job and earn $7.75 per hour. You make $6.75 per hour at the 2nd job. How
many hours will you have to work at the 2nd job if you want to make a total of
$250 per week with both jobs together? Write an equation and solve.
.
25(7.75) + 6.25x = 250
x = 9 hours
The bill to fix your home air conditioner was $824.14. The parts cost $425.14
and the service technician charged $55.00 per hour in labor costs. Write an
equation and solve for how many hours the mechanic takes to fix your car?
425.14 + 45x = 824.14
x = 8.87 hours
Objective
• I can graph linear equations.
Vocabulary
•
•
•
•
•
X intercept
Y intercept
Slope
Slope intercept form
Standard form
X intercept
An x-intercept is a point in the equation where the
y-value is zero
Where the graph intersects the x axis
Also referred to as “root”, “solution”,
“zeroes”
Y intercept
A y-intercept is a point in the equation where the
x-value is zero.
Where the graph intersects the y
axis
Represented with the
letter “b”
Slope
Rise/Run
Represented by “m”
How steep or flat a
line is
Why the letter m???
Nobody knows!
Slope Intercept Form
Y = mx + b
m represents?
Slope of the line
b represents?
Y intercept or where the graph crosses the y axis
(remember b for where to begin the graph)
Practice
• Complete table and graph
y = (-3/4)x + 3
x
-2
-1
0
1
2
y
x intercept ( ,
y intercept ( ,
x
-2
-1
0
)
)
1
2
y
y = -(2/5)x – 2
x intercept ( ,
y intercept ( ,
)
)
Standard Form
Ax + By = C
Can graph using x and y intercepts
Use cover up method to find intercepts
2x + 5y = 10
X intercept
(5, 0)
Y intercept
(0, 2)
Graph using standard form
• 2x + 6y = 12
x
y
-2
-1
0
• X intercept (
• Y intercept (
1
2
,
,
)
)
Convert to Slope-Intercept Form
• Find the slope and y intercept, then graph
-2x + 3y = 9
3y = 2x + 9
Y = (2/3)x + 3
2/3
Slope =
Y intercept 3
.
(Add 2x to both sides)
(Divide both sides by 3)
Practice