73.74.75.76.77.Concept Check If you are solving a formula for the letter k, and your steps lead to the
equation , what would be your next step?
78.Refer to Example 7,and show that 7 is a solution.Solve each formula for the specified variable. See Examples 8 and 9.- for F 80. for E 81. for a
- for R 83. for R 84. for r
- for 86. for S
- for a 88. for B
- for y 90. for q
- for t 92. for r
- for z 94. for p
- 5
y+ 2
- 5
- r
y- 2
=
3
y^2 - 4for r
t
x- 1- 2
x+ 1
=
1
x^2 - 1for t- 3 t-
4
p
=
6
s9 x+
3
z=
5
y5
p+2
q+3
r= 12
r+3
s+1
t= 13
k
=1
p
+1
q1
x
=1
y1
zh=2 a
B+b
d=2 S
n 1 a+L 2d=
2 S
n 1 a+L 2h= a
2 a
B+bI=
E
R+rI=
E
R+rI=
kE
Rm=kF
a
I=kE
Rm=kF
akr-mr=km3
r^2 +r- 21
r^2 - 1
=7
21 r^2 + 3 r+ 22x+ 4
x^2 - 3 x+ 2- 5
x^2 - 4 x+ 3
=
x- 4
x^2 - 5 x+ 6m
m^2 +m- 2+
m
m^2 - 1=
m
m^2 + 3 m+ 23 x
x^2 + 5 x+ 6=5 x
x^2 + 2 x- 32
x^2 +x- 2- 13
t^2 + 6 t+ 8
4
t+ 2
=3
2 t+ 84
3 x+ 63
x+ 3
=8
x^2 + 5 x+ 6x
x- 3+
4
x+ 3=
18
x^2 - 91
x+ 4+
x
x- 4=- 8
x^2 - 16
10 x- 24
x=x
8 x+ 3
x= 3 x5 t+ 1
3 t+ 3=5 t- 5
5 t+ 5+3 t- 1
t+ 1x
2 x+ 2=- 2 x
4 x+ 4
+2 x- 3
x+ 15
p- 2
= 7 -10
p+ 22
x- 12
3
=- 1
x+ 1
m
8 m+ 3
=1
3 m5 x
14 x+ 3
=1
x2 x
x^2 - 16- 2
x- 4
=
4
x+ 42 p
p^2 - 1=
2
p+ 1- 1
p- 1
2 k+ 3
k+ 1- 3 k
2 k+ 2
=- 2 k
2 k+ 2
x
3 x+ 3=
2 x- 3
x+ 1- 2 x
3 x+ 3
464 CHAPTER 7 Rational Expressions and Applications
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