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Elementary Algebra

John Redden

Chapter 9

Solving Quadratic Equations and Graphing Parabolas - all with Video Answers

Educators


Section 1

Extracting Square Roots

01:12

Problem 1

Solve by factoring and then solve by extracting roots. Check answers.
$$
x 2-36=0
$$

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01:05

Problem 2

Solve by factoring and then solve by extracting roots. Check answers.
$$
x 2-81=0
$$

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01:11

Problem 3

Solve by factoring and then solve by extracting roots. Check answers.
$$
4 y 2-9=0
$$

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01:15

Problem 4

Solve by factoring and then solve by extracting roots. Check answers.
$$
9 y 2-25=0
$$

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02:17

Problem 5

Solve by factoring and then solve by extracting roots. Check answers.
$$
(x-2) 2-1=0
$$

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01:35

Problem 6

Solve by factoring and then solve by extracting roots. Check answers.
$$
(x+1) 2-4=0
$$

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02:40

Problem 7

Solve by factoring and then solve by extracting roots. Check answers.
$$
4(y-2) 2-9=0
$$

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02:16

Problem 8

Solve by factoring and then solve by extracting roots. Check answers.
$$
9(y+1) 2-4=0
$$

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01:24

Problem 9

Solve by factoring and then solve by extracting roots. Check answers.
$$
-3(t-1) 2+12=0
$$

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01:26

Problem 10

Solve by factoring and then solve by extracting roots. Check answers.
$$
-2(t+1) 2+8=0
$$

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01:18

Problem 11

Solve by factoring and then solve by extracting roots. Check answers.
$$
(x-5) 2-25=0
$$

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01:24

Problem 12

Solve by factoring and then solve by extracting roots. Check answers.
$$
(x+2) 2-4=0
$$

Teresa Fuston
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01:02

Problem 13

Solve by extracting the roots.
$$
x_{2}=16
$$

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01:02

Problem 14

Solve by extracting the roots.
$$
x_{2}=1
$$

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01:02

Problem 15

Solve by extracting the roots.
$$
y 2=9
$$

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01:03

Problem 16

Solve by extracting the roots.
$$
y 2=64
$$

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01:09

Problem 17

Solve by extracting the roots.
$$
x 2=14
$$

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01:05

Problem 18

Solve by extracting the roots.
$$
x 2=19
$$

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01:15

Problem 19

Solve by extracting the roots.
$$
y 2=0.25
$$

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01:14

Problem 20

Solve by extracting the roots.
$$
y 2=0.04
$$

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01:04

Problem 21

Solve by extracting the roots.
$$
x_{2}=12
$$

Teresa Fuston
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01:05

Problem 22

Solve by extracting the roots.
$$
x 2=18
$$

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01:08

Problem 23

Solve by extracting the roots.
$$
16 x 2=9
$$

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01:02

Problem 24

Solve by extracting the roots.
$$
4 x 2=25
$$

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01:12

Problem 25

Solve by extracting the roots.
$$
2 t 2=1
$$

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01:09

Problem 26

Solve by extracting the roots.
$$
3 t 2=2
$$

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01:02

Problem 27

Solve by extracting the roots.
$$
x_{2}-100=0
$$

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01:00

Problem 28

Solve by extracting the roots.
$$
x_{2}-121=0
$$

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01:12

Problem 29

Solve by extracting the roots.
$$
y 2+4=0
$$

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01:09

Problem 30

Solve by extracting the roots.
$$
y 2+1=0
$$

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01:02

Problem 31

Solve by extracting the roots.
$$
x 2-49=0
$$

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01:10

Problem 32

Solve by extracting the roots.
$$
x_{2}-925=0
$$

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01:16

Problem 33

Solve by extracting the roots.
$$
y 2-0.09=0
$$

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01:04

Problem 34

Solve by extracting the roots.
$$
y 2-0.81=0
$$

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01:03

Problem 35

Solve by extracting the roots.
$$
x_{2}-7=0
$$

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01:05

Problem 36

Solve by extracting the roots.
$$
x_{2}-2=0
$$

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01:01

Problem 37

Solve by extracting the roots.
$$
x_{2}-8=0
$$

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01:01

Problem 38

Solve by extracting the roots.
$$
t 2-18=0
$$

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01:08

Problem 39

Solve by extracting the roots.
$$
x_{2}+8=0
$$

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01:03

Problem 40

Solve by extracting the roots.
$$
x_{2}+125=0
$$

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01:15

Problem 41

Solve by extracting the roots.
$$
16 x 2-27=0
$$

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01:02

Problem 42

Solve by extracting the roots.
$$
9 x 2-8=0
$$

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01:15

Problem 43

Solve by extracting the roots.
$$
2 y 2-3=0
$$

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01:12

Problem 44

Solve by extracting the roots.
$$
5 y 2-2=0
$$

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01:07

Problem 45

Solve by extracting the roots.
$$
3 x 2-1=0
$$

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01:09

Problem 46

Solve by extracting the roots.
$$
6 x 2-3=0
$$

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01:04

Problem 47

Solve by extracting the roots.
$$
(x+7) 2-4=0
$$

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01:01

Problem 48

Solve by extracting the roots.
$$
(x+9) 2-36=0
$$

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01:04

Problem 49

Solve by extracting the roots.
$$
(2 y-3) 2-81=0
$$

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01:03

Problem 50

Solve by extracting the roots.
$$
(2 y+1) 2-25=0
$$

Teresa Fuston
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01:04

Problem 51

Solve by extracting the roots.
$$
(x-5) 2-20=0
$$

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01:01

Problem 52

Solve by extracting the roots.
$$
(x+1) 2-28=0
$$

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01:01

Problem 53

Solve by extracting the roots.
$$
(3 t+2) 2-6=0
$$

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01:01

Problem 54

Solve by extracting the roots.
$$
(3 t-5) 2-10=0
$$

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01:07

Problem 55

Solve by extracting the roots.
$$
4(y+2) 2-3=0
$$

Teresa Fuston
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01:05

Problem 56

Solve by extracting the roots.
$$
9(y-7) 2-5=0
$$

Teresa Fuston
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01:43

Problem 57

Solve by extracting the roots.
$$
4(3 x+1) 2-27=0
$$

Teresa Fuston
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01:16

Problem 58

Solve by extracting the roots.
$$
9(2 x-3) 2-8=0
$$

Teresa Fuston
Teresa Fuston
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01:03

Problem 59

Solve by extracting the roots.
$$
2(3 x-1) 2+3=0
$$

Teresa Fuston
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01:25

Problem 60

Solve by extracting the roots.
$$
5(2 x-1) 2-3=0
$$

Teresa Fuston
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01:19

Problem 61

Solve by extracting the roots.
$$
3(y-23) 2-32=0
$$

Teresa Fuston
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01:14

Problem 62

Solve by extracting the roots.
$$
2(3 y-13) 2-52=0
$$

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01:01

Problem 63

Find a quadratic equation in standard form with the following solutions.
$$
\pm 7
$$

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01:03

Problem 64

Find a quadratic equation in standard form with the following solutions.
$$
\pm 13
$$

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01:09

Problem 65

Find a quadratic equation in standard form with the following solutions.
$$
\pm 7 \sqrt{ }
$$

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01:08

Problem 66

Find a quadratic equation in standard form with the following solutions.
$$
\pm 3 \sqrt{ }
$$

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01:08

Problem 67

Find a quadratic equation in standard form with the following solutions.
$$
\pm 35 \sqrt{ }
$$

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01:03

Problem 68

Find a quadratic equation in standard form with the following solutions.
$$
\pm 52 \sqrt{ }
$$

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01:03

Problem 69

Find a quadratic equation in standard form with the following solutions.
$$
1 \pm 2 \sqrt{ }
$$

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01:04

Problem 70

Find a quadratic equation in standard form with the following solutions.
$$
2 \pm 3 \sqrt{ }
$$

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01:01

Problem 71

Solve and round off the solutions to the nearest hundredth.
$$
9 x(x+2)=18 x+1
$$

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01:05

Problem 72

Solve and round off the solutions to the nearest hundredth.
$$
x_{2}=10(x 2-2)-5
$$

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01:28

Problem 73

Solve and round off the solutions to the nearest hundredth.
$$
(x+3)(x-7)=11-4 x
$$

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01:19

Problem 74

Solve and round off the solutions to the nearest hundredth.
$$
(x-4)(x-3)=66-7 x
$$

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01:16

Problem 75

Solve and round off the solutions to the nearest hundredth.
$$
(x-2) 2=67-4 x
$$

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01:06

Problem 76

Solve and round off the solutions to the nearest hundredth.
$$
(x+3) 2=6 x+59
$$

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01:49

Problem 77

Solve and round off the solutions to the nearest hundredth.
$$
(2 x+1)(x+3)-(x+7)=(x+3) 2
$$

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01:33

Problem 78

Solve and round off the solutions to the nearest hundredth.
$$
(3 x-1)(x+4)=2 x(x+6)-(x-3)
$$

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01:01

Problem 79

Set up an algebraic equation and use it to solve the following.
If 9 is subtracted from 4 times the square of a number, then the result is 3 . Find the number.

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01:01

Problem 80

Set up an algebraic equation and use it to solve the following.
If 20 is subtracted from the square of a number, then the result is $4 .$ Find the number.

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01:04

Problem 81

Set up an algebraic equation and use it to solve the following.
If 1 is added to 3 times the square of a number, then the result is 2 . Find the number.

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01:03

Problem 82

Set up an algebraic equation and use it to solve the following.
If 3 is added to 2 times the square of a number, then the result is 12 . Find the number.

Teresa Fuston
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01:08

Problem 83

Set up an algebraic equation and use it to solve the following.
If a square has an area of 8 square centimeters, then find the length of each side.

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01:17

Problem 84

Set up an algebraic equation and use it to solve the following.
If a circle has an area of $32 \pi$ square centimeters, then find the length of the radius.

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01:34

Problem 85

Set up an algebraic equation and use it to solve the following.
The volume of a right circular cone is $36 \pi$ cubic centimeters when the height is 6 centimeters. Find the radius of the cone. (The volume of a right circular cone is given by $V=13 \pi r 2 h .)$

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01:11

Problem 86

Set up an algebraic equation and use it to solve the following.
The surface area of a sphere is $75 \pi$ square centimeters. Find the radius of the sphere. (The surface area of a sphere is given by $S A=4 \pi r 2 .$

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01:19

Problem 87

Set up an algebraic equation and use it to solve the following.
The length of a rectangle is 6 times its width. If the area is 96 square inches, then find the dimensions of the rectangle.

Teresa Fuston
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01:09

Problem 88

Set up an algebraic equation and use it to solve the following.
The base of a triangle is twice its height. If the area is 16 square centimeters, then find the length of its base.

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01:34

Problem 89

Set up an algebraic equation and use it to solve the following.
A square has an area of 36 square units. By what equal amount will the sides have to be increased to create a square with double the given area?

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01:47

Problem 90

A circle has an area of $25 \pi$ square units. By what amount will the radius have to be increased to create a circle with double the given area?

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01:04

Problem 91

If the sides of a square measure 1 unit, then find the length of the diagonal.

Teresa Fuston
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01:06

Problem 92

If the sides of a square measure 2 units, then find the length of the diagonal.

Teresa Fuston
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01:01

Problem 93

The diagonal of a square measures 5 inches. Find the length of each side.

Teresa Fuston
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01:00

Problem 94

The diagonal of a square measures 3 inches. Find the length of each side.

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01:22

Problem 95

The length of a rectangle is twice its width. If the diagonal measures 10 feet, then find the dimensions of the rectangle.

Teresa Fuston
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01:39

Problem 96

The length of a rectangle is twice its width. If the diagonal measures 8 feet, then find the dimensions of the rectangle.

Teresa Fuston
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01:44

Problem 97

The length of a rectangle is 3 times its width. If the diagonal measures 5 meters, then find the dimensions of the rectangle.

Teresa Fuston
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01:18

Problem 98

The length of a rectangle is 3 times its width. If the diagonal measures 2 feet, then find the dimensions of the rectangle.

Teresa Fuston
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01:14

Problem 99

The height in feet of an object dropped from a 9-foot ladder is given by $h(t)=-16 t 2+9,$ where $t$ represents the time in seconds after the object has been dropped. How long does it take the object to hit the ground? (Hint: The height is 0 when the object hits the ground.)

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01:06

Problem 100

The height in feet of an object dropped from a 20-foot platform is given by $h(t)=-16 t 2+20,$ where $t$ represents the time in seconds after the object has been dropped. How long does it take the object to hit the ground?

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02:02

Problem 101

The height in feet of an object dropped from the top of a 144 -foot building is given by $h(t)=-16 t 2+144,$ where $t$ is measured in seconds.
a. How long will it take to reach half of the distance to the ground, 72 feet?
b. How long will it take to travel the rest of the distance to the ground?

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01:50

Problem 102

The height in feet of an object dropped from an airplane at 1,600 feet is given by $h(t)=-16 t 2+1,600,$ where $t$ is in seconds.
a. How long will it take to reach half of the distance to the ground?
b. How long will it take to travel the rest of the distance to the ground? Round off to the nearest hundredth of a second.

Teresa Fuston
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01:03

Problem 103

Create an equation of your own that can be solved by extracting the root. Share it, along with the solution, on the discussion board.

Teresa Fuston
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01:30

Problem 104

Explain why the technique of extracting roots greatly expands our ability to solve quadratic equations.

Teresa Fuston
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01:29

Problem 105

Explain in your own words how to solve by extracting the roots.

Teresa Fuston
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01:05

Problem 106

Derive a formula for the diagonal of a square in terms of its sides.

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