Chapter 9
What is a dependent variable?
a variable whose value is determined by the value of another quantity.
Apples are on sale for $1.99 a pound. Kassandra buys p pounds of apples for a total cost of c dollars.
Identify the dependent variable:
c
Use the equation to complete the input of 2 (substitute 2 for x):
y=3x+1
7
Solve for y
y=x+1
x=2
y=3
Solve for y
y=x-2
x=2
y=0
What is an independent variable?
a variable whose value determines the value of another quantity.
Apples are on sale for $1.99 a pound. Kassandra buys p pounds of apples for a total cost of c dollars.
Identify the independent variable:
p
Use the equation to complete the input of 4 (substitute 2 for x):
y=3x+1
13
Solve for y
y=x+1
x=4
y=5
Solve for y
y=x-2
x=4
y=2
What is a linear equation?
an equation whose solutions form a straight line on a coordinate plane?
Apples are on sale for $1.99 a pound. Kassandra buys p pounds of apples for a total cost of c dollars.
Identify the equation:
c = 1.99p
Use the equation to complete the input of 6 (substitute 2 for x):
y=3x+1
19
Solve for y
y=x+1
x=6
y=7
Solve for y
y=x-2
x=6
y=4
What variable is the independent variable? x or y?
x
Apples are on sale for $1.99 a pound. Kassandra buys p pounds of apples for a total cost of c dollars.
How much would 3 pounds of apples cost?
$5.97
Write an equation for the relationship in the following:
x 8 9 10 11
y 16 18 ? 22
y=7x
Solve for y
y=x+1
x=8
y=9
Solve for y
y=x-2
x=8
y=6
What variable is the dependent variable? x or y?
y
Apples are on sale for $1.99 a pound. Kassandra buys p pounds of apples for a total cost of c dollars.
How much would 10 pounds cost?
$19.90
What is the ?
x 8 9 10 11
y 16 18 ? 22
49
Solve for y
y=x+1
x=10
y=11
Solve for y
y=x-2
x=10
y=8