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Basic Technical Mathematics with Calculus

Allyn J. Washington, Richard S. Evans

Chapter 17

Inequalities - all with Video Answers

Educators


Section 1

Properties of Inequalities

00:23

Problem 1

In Exercises $1-4,$ make the given changes in the indicated examples of this section and then perform the indicated operations.
In Example $2,$ in the first paragraph, change the $ > $ to $ < $ and then complete the meaning of the resulting inequality as in the first sentence. Rewrite the meaning as in the second line.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:29

Problem 2

In Exercises $1-4,$ make the given changes in the indicated examples of this section and then perform the indicated operations.
In Example $4(\mathrm{b}),$ change $\leq$ to $>$ and then graph the resulting inequality.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:58

Problem 3

In Exercises $1-4,$ make the given changes in the indicated examples of this section and then perform the indicated operations.
In Example $7,$ change the inequality to $-2>-4$ and then perform the two operations shown in color.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:32

Problem 4

In Exercises $1-4,$ make the given changes in the indicated examples of this section and then perform the indicated operations.
In Example $9(b),$ change the -1 to -3 and the 3 to 1 and then write the two forms in which an inequality represents the statement.

Wendi Zhao
Wendi Zhao
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00:18

Problem 5

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Add 5

Wendi Zhao
Wendi Zhao
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00:19

Problem 6

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Subtract 16

Wendi Zhao
Wendi Zhao
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00:19

Problem 7

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Multiply by 4

Wendi Zhao
Wendi Zhao
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00:21

Problem 8

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Multiply by -2

Wendi Zhao
Wendi Zhao
Numerade Educator
00:20

Problem 9

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Divide by -1

Wendi Zhao
Wendi Zhao
Numerade Educator
00:18

Problem 10

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Divide by 0.5

Wendi Zhao
Wendi Zhao
Numerade Educator
00:25

Problem 11

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Square both.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:26

Problem 12

In Exercises $5-12,$ for the inequality $4<9,$ state the inequality that results when the given operations are performed on both members.
Take square roots.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:12

Problem 13

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Greater than -2

Wendi Zhao
Wendi Zhao
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00:12

Problem 14

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Less than 0.7

Wendi Zhao
Wendi Zhao
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00:15

Problem 15

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Less than or equal to 38

Wendi Zhao
Wendi Zhao
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00:13

Problem 16

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Greater than or equal to -6

Wendi Zhao
Wendi Zhao
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00:23

Problem 17

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Greater than 1 and less than 7

Wendi Zhao
Wendi Zhao
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00:37

Problem 18

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Greater than or equal to -200 and less than 650

Wendi Zhao
Wendi Zhao
Numerade Educator
00:39

Problem 19

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Less than $-5,$ or greater than or equal to 3

Wendi Zhao
Wendi Zhao
Numerade Educator
00:40

Problem 20

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Less than or equal to $8,$ or greater than or equal to 12

Wendi Zhao
Wendi Zhao
Numerade Educator
00:32

Problem 21

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Less than $1,$ or greater than 3 and less than or equal to 5

Wendi Zhao
Wendi Zhao
Numerade Educator
00:32

Problem 22

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Greater than or equal to 0 and less than or equal to $2,$ or greater than 5

Wendi Zhao
Wendi Zhao
Numerade Educator
00:24

Problem 23

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Greater than -2 and less than $2,$ or greater than or equal to 3 and less than 4

Wendi Zhao
Wendi Zhao
Numerade Educator
00:33

Problem 24

In Exercises $13-24,$ give the inequalities equivalent to the following statements about the number $x .$
Less than $-4,$ or greater than or equal to 0 and less than or equal to $1,$ or greater than or equal to 5

Wendi Zhao
Wendi Zhao
Numerade Educator
00:24

Problem 25

In Exercises $25-28,$ give verbal statements equivalent to the given inequalities involving the number $x$.
$$0<x \leq 9$$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:18

Problem 26

In Exercises $25-28,$ give verbal statements equivalent to the given inequalities involving the number $x$.
$$x < 5 \text { or } x > 7$$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:30

Problem 27

In Exercises $25-28,$ give verbal statements equivalent to the given inequalities involving the number $x$.
$$x < -10 \text { or } 10 \leq x < 20$$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:39

Problem 28

In Exercises $25-28,$ give verbal statements equivalent to the given inequalities involving the number $x$.
$$-1 \leq x < 3 \text { or } 5 < x < 7$$

Wendi Zhao
Wendi Zhao
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00:36

Problem 29

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x < 3$$

Wendi Zhao
Wendi Zhao
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00:36

Problem 30

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x \geq-1$$

Wendi Zhao
Wendi Zhao
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01:02

Problem 31

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x \leq-1 \text { or } x > 0.5$$

Wendi Zhao
Wendi Zhao
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00:53

Problem 32

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x < -300 \text { or } x \geq 0$$

Wendi Zhao
Wendi Zhao
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00:43

Problem 33

In Exercises $29-44,$ graph the given inequalities on the number line.
$$0 \leq x < 5$$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:25

Problem 34

In Exercises $29-44,$ graph the given inequalities on the number line.
$$-4 < y < -2$$

Wendi Zhao
Wendi Zhao
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00:29

Problem 35

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x \geq-3 \text { and } x < 5$$

Wendi Zhao
Wendi Zhao
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00:17

Problem 36

In Exercises $29-44,$ graph the given inequalities on the number line.
$x>4$ and $x<3$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:37

Problem 37

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x < -1 \text { or } 1 \leq x < 4$$

Wendi Zhao
Wendi Zhao
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00:44

Problem 38

In Exercises $29-44,$ graph the given inequalities on the number line.
$$-3 < x < 0 \text { or } x > 3$$

Wendi Zhao
Wendi Zhao
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00:45

Problem 39

In Exercises $29-44,$ graph the given inequalities on the number line.
$$-3 < x < -1 \text { or } 0.5 < x \leq 3$$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:30

Problem 40

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x \leq 4 \text { or } x > -4$$

Wendi Zhao
Wendi Zhao
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00:22

Problem 41

In Exercises $29-44,$ graph the given inequalities on the number line.
$$t \leq-5 \text { and } t \geq-5$$

Wendi Zhao
Wendi Zhao
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00:30

Problem 42

In Exercises $29-44,$ graph the given inequalities on the number line.
$$x < 1 \text { or } 1 < x \leq 4$$

Wendi Zhao
Wendi Zhao
Numerade Educator
01:50

Problem 43

In Exercises $29-44,$ graph the given inequalities on the number line.
$$(x \leq 5 \text { or } x \geq 8) \text { and }(3 < x < 10)$$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:54

Problem 44

In Exercises $29-44,$ graph the given inequalities on the number line.
$(x < 7 \text { and } x > 2)$ or $(x \geq 10 \text { or } x < 1)$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:26

Problem 45

In Exercises $45-48,$ answer the given questions about the inequality $0 < a < b$.
Is $a^{2} < b^{2}$ a conditional inequality or an absolute inequality?

Wendi Zhao
Wendi Zhao
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00:26

Problem 46

In Exercises $45-48,$ answer the given questions about the inequality $0 < a < b$.
Is $|a-b| < b-a ?$

Wendi Zhao
Wendi Zhao
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00:44

Problem 47

In Exercises $45-48,$ answer the given questions about the inequality $0 < a < b$.
If each member of the inequality $2 > 1$ is multiplied by $a-b,$ is the result $2(a-b) > (a-b) ?$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:45

Problem 48

In Exercises $45-48,$ answer the given questions about the inequality $0 < a < b$.
What is wrong with the following sequence of steps?
$a < b, a b < b^{2}, a b-b^{2} < 0, b(a-b) < 0, b < 0$

Wendi Zhao
Wendi Zhao
Numerade Educator
02:44

Problem 49

In Exercises $49-52,$ solve the given problems.
Write the relationship between $(|x|+|y|)$ and $|x+y|$ if $x > 0$ and $y < 0$

Wendi Zhao
Wendi Zhao
Numerade Educator
01:02

Problem 50

In Exercises $49-52,$ solve the given problems.
Write the relationship between $|x y|$ and $|x||y|$ if $x > 0$ and $y < 0$.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:32

Problem 51

In Exercises $49-52,$ solve the given problems.
Explain the error in the following "proof" that $3 < 2$ (1) $1 / 8 < 1 / 4 \quad$ (2) $0.5^{3} < 0.5^{2} \quad$ (3) $\log 0.5^{3} < \log 0.5^{2}$ (4) $3 \log 0.5 < 2 \log 0.5 \quad(5) 3 < 2$

Wendi Zhao
Wendi Zhao
Numerade Educator
00:58

Problem 52

In Exercises $49-52,$ solve the given problems.
If $x \neq y,$ show that $x^{2}+y^{2} > 2 x y$

Wendi Zhao
Wendi Zhao
Numerade Educator
01:29

Problem 53

In Exercises $53-62,$ some applications of inequalities are shown.
The length $L$ and width $w$ (in yd) of a rectangular soccer field should satisfy the inequalities $110 \leq L \leq 120$ and $70 \leq w \leq 80$ Express the possible diagonal lengths $d$ as an inequality.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:37

Problem 54

In Exercises $53-62,$ some applications of inequalities are shown.
A breakfast cereal company guarantees the calorie count shown for each serving is accurate within $5 \% .$ If the package shows a serving has 200 cal, write an inequality for the possible calorie counts.

Wendi Zhao
Wendi Zhao
Numerade Educator
00:29

Problem 55

In Exercises $53-62,$ some applications of inequalities are shown.
An electron microscope can magnify an object from 2000 times to 1,000,000 times. Assuming these values are exact, express these magnifications $M$ as an inequality and graph them.

Wendi Zhao
Wendi Zhao
Numerade Educator
01:05

Problem 56

In Exercises $53-62,$ some applications of inequalities are shown.
A busy person glances at a digital clock that shows $9: 36 .$ Another glance a short time later shows the clock at $9: 44 .$ Express the amount of time $t$ (in min) that could have elapsed between glances by use of inequalities. Graph these values of $t$.

Audrey Fong
Audrey Fong
Numerade Educator
01:02

Problem 57

In Exercises $53-62,$ some applications of inequalities are shown.
An Earth satellite put into orbit near Earth's surface will have an elliptic orbit if its velocity $v$ is between $18,000 \mathrm{mi} / \mathrm{h}$ and $25,000 \mathrm{mi} / \mathrm{h} .$ Write this as an inequality and graph these values of $v$.

Audrey Fong
Audrey Fong
Numerade Educator
01:07

Problem 58

In Exercises $53-62,$ some applications of inequalities are shown.
Fossils found in Jurassic rocks indicate that dinosaurs flourished during the Jurassic geological period, 140 MY (million years ago) to 200 MY. Write this as an inequality, with $t$ representing past time. Graph the values of $t$.

Audrey Fong
Audrey Fong
Numerade Educator
01:24

Problem 59

In Exercises $53-62,$ some applications of inequalities are shown.
A DVD player spins at 1530 r/min at the innermost edge and gradually slows to a rate of $630 \mathrm{r} / \mathrm{min}$ at the outer edge. Use an inequality to express the angular velocity $\omega$ of the DVD player.

Audrey Fong
Audrey Fong
Numerade Educator
01:09

Problem 60

In Exercises $53-62,$ some applications of inequalities are shown.
The velocity $v$ of an ultrasound wave in soft human tissue may be represented as $1550 \pm 60 \mathrm{m} / \mathrm{s},$ where the $\pm 60 \mathrm{m} / \mathrm{s}$ gives the possible variation in the velocity. Express the possible velocities by an inequality.

Audrey Fong
Audrey Fong
Numerade Educator
01:57

Problem 61

In Exercises $53-62,$ some applications of inequalities are shown.
A driver using the Google Maps app finds that it is 300 mi to her destination. If her speed always stays between $50 \mathrm{mi} / \mathrm{h}$ and $60 \mathrm{mi} / \mathrm{h}$ use an inequality to express the required time $t$ for the trip.

Audrey Fong
Audrey Fong
Numerade Educator
02:47

Problem 62

In Exercises $53-62,$ some applications of inequalities are shown.
If the current from the source in Example 12 is $i=5 \cos 4 \pi t$ and the diode allows only negative current to flow, write the inequalities and draw the graph for the current in the circuit as a function of time for $0 \leq t \leq 1 s$.

Stanley Enemuo
Stanley Enemuo
Numerade Educator