Download 4-5 Practice A,B,C packet

Name _______________________________________ Date __________________ Class __________________
Algebra IB
4-5 Practice A Direct Variation
Complete the table.
1. y  7x
Solve for y
(if needed).
Is the equation in
the form y  kx?
Is it a direct
variation?
y  7x
yes
yes
Constant of
variation
2. y  4x  10
3. 5x  2y  0
For 4 – 5 , tell whether each relationship is a direct variation. Explain.
4.
x
10 15 20
y
2
3
4
6.The value of y varies directly with x,
and y  2 when x  4.
Find y when x  8.
5.
x
4
8
12
y
16 20 24
7.The value of y varies directly with x,
and y  12 when x  8.
Find y when x  15.
8. The number of hamburgers that can be
made varies directly with the weight of
ground beef used. Four hamburgers can
be produced from every pound of ground
beef. Write a direct variation equation for
the number of hamburgers y that can be
produced from x pounds of ground beef.
Then graph the relationship.
________________________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
Holt McDougal Algebra 1
Name _______________________________________ Date __________________ Class __________________
Practice B
Direct Variation
Tell whether each equation is a direct variation. If so, identify the
constant of variation.
1. y  3x _________________
2. y  2x  9 _________________
3. 2x  3y  0 _________________
4. 3y  9x _________________
For 5 –7 , tell whether each relationship is a direct variation. Explain.
5.
x
6
15
21
y
2
5
7
________________________
6.
x
6
10
25
y
24
40
100
________________________
8. The value of y varies directly with x,
and y  18 when x  6.
Find y when x  8.
7.
x
10
15
20
y
3
5
9
________________________
9. The value of y varies directly with x,
1
and y 
when x  5.
2
Find y when x  30.
10. The amount of interest earned in a savings account
varies directly with the amount of money in the account.
A certain bank offers a 2% savings rate. Write a direct
variation equation for the amount of interest y earned
on a balance of x. Then graph.
________________________________________
11. Another bank offers a different savings rate. If an
account with $400 earns interest of $6, how much
interest is earned by an account with $1800?
________________________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
Holt McDougal Algebra 1
Name _______________________________________ Date __________________ Class __________________
Practice C
Direct Variation
Tell whether each equation is a direct variation. If so, identify the
constant of variation.
1. y  2x _________________
2. 8y  3x  1 _________________
3. 12y  24x _________________
4. 5x  9y  0 _________________
5. 6x  3  y _________________
6. y  4x  8 _________________
For 7–9, tell whether each relationship is a direct variation. Explain.
7.
x
3
6
9
y
18
36
54
8.
x
8
0
5
y
13
5
0
9.
x
1
5
8
y
1.5
7.5
12
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10. The value of y varies directly with x, and y  14 when x 
1
.
2
Find y when x  1. ___________________________
11.The value of y varies directly with x, and y  9 when x  2.
Find x when y  22.5. ___________________________
12.The area a painter can paint varies directly with the
amount of time he works. One morning, he painted 204 ft2
between 8 a.m. and 12:15 a.m. Write a direct variation
equation to describe the area y covered in x hours.
_________________________
13. The number of people that can be seated in a lecture
hall varies directly with the number of rows of seats. If
72 people can be seated in 4 rows, write a direct variation
equation to describe the number of people y that can be
seated in x rows. Then graph.
________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
Holt McDougal Algebra 1