Name ___________________
Date ___________
Algebra I
Unit 10 Day 3 Direct and Inverse Variation
Direct Variation _____________________, where k is the ___________ of
variation or __________.
Do the following equations represent direct variation? If so, identify the constant.
1
x
2
y = -2x + 3
y=
2x – 3y = 0
x+y=4
Graphing direct variation equations.
Direct variation equations always go through the _____________________.
y=
2
x
3
y = -x
Write direct variation equations for the following.
Y and x vary directly. Write a direct variation equation that relates x and y. Find
the value of y when x = 14.
x = 3, y = 6
x = -2, y = 18
x = 10, y = 5
x=
1
,y=2
4
Bryan works a part-time job and his paycheck total varies directly with the number
of hours that he works. Write a direct variation equation that relates Brian’s total
paycheck and number of hours if he makes $111 for working 12 hours.
How much will Bryan earn if he works 23 hours?
How many hours does Bryan work if he makes $157.25
Inverse Variation __________, where k is the _______________ of variation.
Tell whether x and y show direct variation, inverse variation or neither. Identify
the constant.
xy = 7
y
x
4
y = -x + 3
x
y
x
y
1
2
3
2
2
4
6
1
4
8
12
1
2
18
1
3
9
18
The variables x and y vary inversely. Use the given values to write an equation
relating x and y. Then find y when x = 3.
x = 5, y = -4
x = 1, y = 9
The number of hours, h, it takes for a block of ice to melt varies inversely as the
temperature, t. Write an equation that relates number of hours with temperature if
it takes 2 hours for a square inch of ice to melt at 65ºF.
How long would it take for an inch of ice to melt at 100ºF?