©
3-8
NAME ______________________________________________ DATE
____________ PERIOD _____
3-8
Skills Practice
1. 7t x, for t
x
t
2. e wp, for p
7
q
3. q r r, for r r 2
5. 7a b 15a, for a
8
x1
y
2
9. 7f g 5, for f
f
7
5g
11. rt 2n y, for t
2n y
t
r
1. d rt, for r
w
9v 4f
n
k
6. 5c d 2c, for c
8. m 3n 1, for n
d
c
12. bc 3g 2k, for c
2. 6w y 2z, for w
t
3c 4y
x
m
4. 9s 5g 4u, for s
5. ab 3c 2d, for b
2d 3c
b
a
6. 2p kx q, for x
2
3
3
m
c
8. h g d, for h
2
3
3
y
(s v)
10. a q k, for a
9. y v s, for y
1m
n
3
2k 3g
c
b
5p 6j
14. 8c 6j 5p, for c c 8
2z y
w
6
3. mx 4y 3c, for x
7. m a a c, for m
7
rx 9
11. h, for x
5
bc
x
a
10. ax c b, for x
d
r
2
2
5h 9
x
r
13. 2w y 7w 2, for w
4u 5g
s 9
2p q
x
k
2
5
5
h
(d g )
3
4
4
a
(k q)
2
3
2c 4
b
3
y5
14. 3 y 5 5, for 2
3b 4
12. c, for b
2
2y
w
5
Write an equation and solve for the variable specified.
15. Three times a number s plus 4 times a number y is 1 more than 6 times the number s.
Solve for s.
4y 1
3s 4y 6s 1; s 3
16. Five times a number k minus 9 is two thirds of a number j. Solve for j.
xc
15. d, for x
2
p9
5
17. q, for p
x c 2d
xc
16. d, for c
2
p 5q 9
18. a, for b
b 4z
7
2
3
5k 9 j; j (5k 9)
c x 2d
b 7a 4z
3
2
ELECTRICITY For Exercises 17 and 18, use the following information.
The formula for Ohm’s Law is E IR, where E represents voltage measured in volts,
I represents current measured in amperes, and R represents resistance measured in ohms.
E
R
Write an equation and solve for the variable specified.
17. Solve the formula for R.
19. Five more than a number g is six less than twice a number h. Solve for g.
18. Suppose a current of 0.25 ampere flows through a resistor connected to a 12-volt battery.
What is the resistance in the circuit? 48 ohms
g 5 2h 6; g 2h 11
I
MOTION For Exercises 19 and 20, use the following information.
20. One fourth of a number q is three more than three times a number w. Solve for q.
1
q 3w 3; q 12w 12
4
Glencoe Algebra 1
where r is the radius of the disk and T is the time it takes the point to travel once around
the circle.
21. Eight less than a number s is three more than four times a number t. Solve for s.
Glencoe/McGraw-Hill
19. Solve the formula for r.
Tv
2
r 20. Suppose a merry-go-round is spinning once every 3 seconds. If a point on the outside
edge has a speed of 12.56 feet per second, what is the radius of the merry-go-round?
(Use 3.14 for .) 6 ft
s 8 4t 3; s 4t 11
©
2
T
In uniform circular motion, the speed v of a point on the edge of a spinning disk is v r,
181
Glencoe Algebra 1
©
Glencoe/McGraw-Hill
182
Glencoe Algebra 1
(Lesson 3-8)
A24
13. kn 4f 9v, for n
e
p
Answers
7. x 2y 1, for y
(Average)
Solve each equation or formula for the variable specified.
n
4. 4m n m, for m m 3
b
a Practice
____________ PERIOD _____
Solving Equations and Formulas
Solving Equations and Formulas
Solve each equation or formula for the variable specified.
Lesson 3-8
Glencoe/McGraw-Hill
NAME ______________________________________________ DATE