Download Practice C 2-7

Name
LESSON
Date
Class
Practice C
2-7 Equations in Two Variables
Write an equation in two variables that gives the values in each
table, and then find the missing terms.
1.
2.
3.
4.
x
3
4
5
6
25
36
y
4
9
x
32
28
y
8
6
5
4
x
1
3
4
5
y
7
12
17
22
8
6
4
2
1.6
0.8
x
y
4
24
16
3.2
Write an equation for the relationship. Tell what each variable
you use represents.
5. The rate of travel is the quotient of the distance traveled divided
by the time spent traveling.
6. A taxi driver charges a flat rate of $3.00 and $0.80 per mile
traveled.
7. Tony earns $12 per hour for 40 hours a week. For any hour over
40, he earns time and a half, which is the sum of the regular
hourly rate and half that rate. Use your equation to find how
much Tony will earn if he works 45 hours next week.
8. Explain why the equation y x 2 can have two possible values
of x for every value of y.
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
59
Holt Mathematics
Practice B
2-7 Equations in Two Variables
Practice A
2-7 Equations in Two Variables
LESSON
LESSON
Write an equation in two variables that gives the values in each
table. Use the equation to find the value of y for the indicated
value of x.
Write an equation in two variables that gives the values in
each table.
1.
2.
x
0
1
2
3
y
2
3
4
5
x
1
2
3
4
y
5
10
15
20
yx2
1.
y 5x
2.
Circle the letter of the equation that correctly describes
each relationship.
3. Carol is 4 years younger than her
brother, Vishu. Let c Carol’s age
and v Vishu’s age.
C cv÷4
A cv4
B c 4v
D c4v
4. If Vishu is 10 years old, how old is
Carol?
F 14 years old
H 6 years old
5. Tim earns $9 for every hour that he
works. Let h the number of hours
Tim works and m amount earned.
A mh9
C mh÷9
D m9h
B m 9h
6. If Tim works 18 hours in one week,
how much will he earn in all?
F $27
H $2
G $9
J $162
G 40 years old
3.
4.
1
J 22 years old
x
1
2
3
4
5
y
7
14
21
28
♦
x
2
3
4
5
6
y
3
2
1
0
♦
x
20
16
12
8
4
y
10
8
6
4
♦
x
7
8
9
10
11
y
11
12
13
14
♦
y 7x
y 35
yx5
y1
yx2
y2
yx4
y 15
Write an equation for the relationship. Tell what each variable
you use represents.
5. Amanda is 7 years younger than her cousin.
Possible answer: y x 7; y Amanda’s age; x her cousin’s age
6. The population of North Carolina is twice as large as the
population of South Carolina.
Write an equation for the relationship. Tell what each variable
you use represents.
Possible answer: n 2s; n population of North Carolina;
7. An extra-large pizza costs $7 more than a personal-size pizza.
Write an equation for this relationship. Tell what each variable
you use represents.
s population of South Carolina
7. An Internet book company charges $7 for each paperback book,
plus $2.75 for shipping and handling per order.
Possible answer: y 7 x ; y price of extra-large pizza;
x price of personal-size pizza
Possible answer: y 7x 2.75; y total price of order;
8. On average, Tamara jogs 10 miles per hour. Write an equation to
show how far Tamara runs in h hours. Tell what each variable
you use represents.
x number of books purchased
8. Henry records how many days he rides his bike and how far he
rides each week. He rides the same distance each time. He rode
18 miles in 3 days, 24 miles in 4 days, and 42 miles in 7 days.
Write an equation in two variables for the relationship.
Possible answer: y 10h, y distance run; h hours run
m 6d; m miles, and d days
57
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Holt Mathematics
Practice C
2-7 Equations in Two Variables
LESSON
In the table below, the x-values are the input and the y-values are
the output.
Write an equation in two variables that gives the values in each
table, and then find the missing terms.
2.
3.
4.
Holt Mathematics
Review for Mastery
2-7 Equations in Two Variables
LESSON
1.
58
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
x
2
3
4
5
6
y
4
9
16
25
36
x
32
28
24
20
16
y
8
7
6
5
4
x
1
2
3
4
5
y
7
12
17
22
27
x
10
8
6
4
2
y
4
3.2
2.4
1.6
0.8
yx2
x 0
1
2
3 4
5
y 4
5
6
7 8
9 10 ?
6 7
To write an equation in two variables for a table of
values, first compare the x- and y-values to find a
pattern.
Each y-value is 4 more than its corresponding
x-value.
y x (4)
Then use the pattern to write a rule for the table.
y 5x 2
yx4
You can use the rule to find a missing value in a table.
To find the value of y in table above when x 7, substitute
7 for x in the equation.
y 0.4x
Write an equation for the relationship. Tell what each variable
you use represents.
yx4
y74
y 11
So y is 11 when x is 7.
Write an equation in two variables that gives the values in each
table. Use the equation to find the value of y for the indicated
value of x.
5. The rate of travel is the quotient of the distance traveled divided
by the time spent traveling.
1.
Possible answer: r d t; r rate; d distance; t time
6. A taxi driver charges a flat rate of $3.00 and $0.80 per mile
traveled.
x 1
2
3
6
2. x 18 17 16 15 14 13
y 3
6
9 12 15 ?
y 15 14 13 ? 11 10
4 5
y 3x, y 18
Possible answer: c 3 0.8m; c total charge; m miles
y x 3, y 12
You can also write equations for relationships that are described in words.
7. Tony earns $12 per hour for 40 hours a week. For any hour over
40, he earns time and a half, which is the sum of the regular
hourly rate and half that rate. Use your equation to find how
much Tony will earn if he works 45 hours next week.
The length of the pool is 6 times the width of the pool.
length of pool
w width of pool
6w
Possible answer: y 480 18h; y total weekly earnings;
h hours worked over 40 hours; $570
Choose variables for the equation.
Write an equation.
Write an equation for the relationship. Tell what each variable
you use represents.
8. Explain why the equation y x 2 can have two possible values
of x for every value of y.
3. Todd is 6 inches taller than Scott.
4. Alana is 4 times as old as Tracey.
because the positive and negative of a number squared have the same
t Todd’s height
a Alana’s age
value: 4 22; 4 (2)2
s Scott’s height
t Tracey’s age
ts6
a 4t
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
59
Copyright © by Holt, Rinehart and Winston.
Holt Mathematics
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
97
60
Holt Mathematics
Holt Mathematics