7.1E: Exercises
- Last updated
- Mar 9, 2020
- Save as PDF
- Page ID
- 30950
( \newcommand{\kernel}{\mathrm{null}\,}\)
Practice Makes Perfect
In the following exercises, determine the values for which the rational expression is undefined.
Example 7.1E.49
- 2xz
- 4p−16p−5
- n−3n2+2n−8
- Answer
-
- z=0
- p=56
- n=−4, n=2
Example 7.1E.50
- 10m11n
- 6y+134y−9
- b−8b2−36
Example 7.1E.51
- 4x2y3y
- 3x−22x+1
- u−1u2−3u−28
- Answer
-
- y=0
- x=−12
- u=−4, u=7
Example 7.1E.52
- 5pq29q
- 7a−43a+5
- 1x2−4
Evaluate Rational Expressions
In the following exercises, evaluate the rational expression for the given values.
Example 7.1E.53
2xx−1
- x=0
- x=2
- x=−1
- Answer
-
- 0
- 4
- 1
Example 7.1E.54
4y−15y−3
- y=0
- y=2
- y=−1
Example 7.1E.55
2p+3p2+1
- p=0
- p=1
- p=−2
- Answer
-
- 3
- 52
- −15
Example 7.1E.56
x+32−3x
- x=0
- x=1
- x=−2
Example 7.1E.57
y2+5y+6y2−1
- y=0
- y=2
- y=−2
- Answer
-
- −6
- 203
- 0
Example 7.1E.58
z2+3z−10z2−1
- z=0
- z=2
- z=−2
Example 7.1E.59
a2−4a2+5a+4
- a=0
- a=1
- a=−2
- Answer
-
- −1
- −310
- 0
Example 7.1E.60
b2+2b2−3b−4
- b=0
- b=2
- b=−2
Example 7.1E.61
x2+3xy+2y22x3y
- x=1, y=−1
- x=2, y=1
- x=−1, y=−2
- Answer
-
- 0
- 34
- 154
Example 7.1E.62
c2+cd−2d2cd3
- c=2, d=−1
- c=1, d=−1
- c=−1, d=2
Example 7.1E.63
m2−4n25mn3
- m=2, n=1
- m=−1, n=−1
- m=3, n=2
- Answer
-
- 0
- −35
- −720
Example 7.1E.64
2s2ts2−9t2
- s=4, t=1
- s=−1, t=−1
- s=0, t=2
Simplify Rational Expressions
In the following exercises, simplify.
Example 7.1E.65
−452
- Answer
-
−113
Example 7.1E.66
−4455
Example 7.1E.67
5663
- Answer
-
89
Example 7.1E.68
65104
Example 7.1E.69
6ab212a2b
- Answer
-
b2a
Example 7.1E.70
15xy3x3y3
Example 7.1E.71
8m3n12mn2
- Answer
-
2m23n
Example 7.1E.72
36v3w227vw3
Example 7.1E.73
3a+64a+8
- Answer
-
34
Example 7.1E.74
5b+56b+6
Example 7.1E.75
3c−95c−15
- Answer
-
35
Example 7.1E.76
4d+89d+18
Example 7.1E.77
7m+635m+45
- Answer
-
75
Example 7.1E.78
8n−963n−36
Exercise 7.1E.79
12p−2405p−100
- Answer
-
125
Example 7.1E.80
6q+2105q+175
Example 7.1E.81
a2−a−12a2−8a+16
- Answer
-
a+3a−4
Example 7.1E.82
x2+4x−5x2−2x+1
Example 7.1E.83
y2+3y−4y2−6y+5
- Answer
-
y+4y−5
Example 7.1E.84
v2+8v+15v2−v−12
Example 7.1E.85
x2−25x2+2x−15
- Answer
-
x−5x−3
Example 7.1E.86
a2−4a2+6a−16
Example 7.1E.87
y2−2y−3y2−9
- Answer
-
y+1y+3
Example 7.1E.88
b2+9b+18b2−36
Example 7.1E.89
y3+y2+y+1y2+2y+1
- Answer
-
y2+1y+1
Example 7.1E.90
p3+3p2+4p+12p2+p−6
Example 7.1E.91
x3−2x2−25x+50x2−25
- Answer
-
x−2
Example 7.1E.92
q3+3q2−4q−12q2−4
Example 7.1E.93
3a2+15a6a2+6a−36
- Answer
-
a(a+5)2(a+3)(a−2)
Example 7.1E.94
8b2−32b2b2−6b−80
Example 7.1E.95
−5c2−10c−10c2+30c+100
- Answer
-
c2(c−5)
Example 7.1E.96
4d2−24d2d2−4d−48
Example 7.1E.97
3m2+30m+754m2−100
- Answer
-
3(m+5)4(m−5)
Example 7.1E.98
5n2+30n+452n2−18
Example 7.1E.99
5r2+30r−35r2−49
- Answer
-
5(r−1)r+7
Example 7.1E.100
3s2+30s+723s2−48
Example 7.1E.101
t3−27t2−9
- Answer
-
t2+3t+9t+3
Example 7.1E.102
v3−1v2−1
Example 7.1E.103
w3+216w2−36
- Answer
-
w2−6w+36w−6
Example 7.1E.104
v3+125v2−25
Simplify Rational Expressions with Opposite Factors
In the following exercises, simplify each rational expression.
Example 7.1E.105
a−55−a
- Answer
-
−1
Example 7.1E.106
b−1212−b
Example 7.1E.107
11−cc−11
- Answer
-
−1
Example 7.1E.108
5−dd−5
Example 7.1E.109
12−2xx2−36
- Answer
-
−2x+6
Example 7.1E.110
20−5yy2−16
Example 7.1E.111
4v−3264−v2
- Answer
-
−48+v
Example 7.1E.112
7w−219−w2
Example 7.1E.113
y2−11y+249−y2
- Answer
-
−y−83+y
Example 7.1E.114
z2−9z+2016−z2
Example 7.1E.115
a2−5a−3681−a2
- Answer
-
−a+49+a
Example 7.1E.116
b2+b−4236−b2
Everyday Math
Example 7.1E.117
Tax Rates For the tax year 2015, the amount of tax owed by a single person earning between $37,450 and $90,750, can be found by evaluating the formula 0.25x−4206.25, where x is income. The average tax rate for this income can be found by evaluating the formula 0.25x−4206.25x. What would be the average tax rate for a single person earning $50,000?
- Answer
-
16.5%
Example 7.1E.118
Work The length of time it takes for two people for perform the same task if they work together can be found by evaluating the formula xyx+y. If Tom can paint the den in x=45 minutes and his brother Bobby can paint it in y=60 minutes, how many minutes will it take them if they work together?
Writing Exercises
Example 7.1E.119
Explain how you find the values of x for which the rational expression x2−x−20x2−4 is undefined.
- Answer
-
Answers will vary, but all should reference setting the denominator function to zero.
Example 7.1E.120
Explain all the steps you take to simplify the rational expression p2+4p−219−p2.
Self Check
ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.
ⓑ If most of your checks were:
…confidently. Congratulations! You have achieved your goals in this section! Reflect on the study skills you used so that you can continue to use them. What did you do to become confident of your ability to do these things? Be specific!
…with some help. This must be addressed quickly as topics you do not master become potholes in your road to success. Math is sequential - every topic builds upon previous work. It is important to make sure you have a strong foundation before you move on. Who can you ask for help? Your fellow classmates and instructor are good resources. Is there a place on campus where math tutors are available? Can your study skills be improved?
…no - I don’t get it! This is critical and you must not ignore it. You need to get help immediately or you will quickly be overwhelmed. See your instructor as soon as possible to discuss your situation. Together you can come up with a plan to get you the help you need.