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Mathematics LibreTexts

9.E: Review Exercises and Sample Exam

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  • Anonymous
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Review Exercises

Exercise 9.E.1 extracting square roots

Solve by extracting the roots.

  1. x216=0
  2. y2=94
  3. x227=0
  4. x2+27=0
  5. 3y225=0
  6. 9x22=0
  7. (x5)29=0
  8. (2x1)21=0
  9. 16(x6)23=0
  10. 2(x+3)25=0
  11. (x+3)(x2)=x+12
  12. (x+2)(5x1)=9x1
Answer

1. ±16

3. ±33

5. ±533

7. 2,8

9. 6±34

11. ±32

Exercise 9.E.2 extracting square roots

Find a quadratic equation in standard form with the given solutions.

  1. ±2
  2. ±25
Answer

1. x22=0

Exercise 9.E.3 completing the square

Complete the square.

  1. x26x+?=(x?)2
  2. x2x+?=(x?)2
Answer

1. x26x+9=(x3)2

Exercise 9.E.4 completing the square

Solve by completing the square.

  1. x212x+1=0
  2. x2+8x+3=0
  3. y24y14=0
  4. y22y74=0
  5. x2+5x1=0
  6. x27x2=0
  7. 2x2+x3=0
  8. 5x2+9x2=0
  9. 2x216x+5=0
  10. 3x26x+1=0
  11. 2y2+10y+1=0
  12. 5y2+y3=0
  13. x(x+9)=5x+8
  14. (2x+5)(x+2)=8x+7
Answer

1. 6±35

3. 2±32

5. 5±292

7. 32,1

9. 8±362

11. 5±232

13. 2±23

Exercise 9.E.5 quadratic formula

Identify the coefficients a, b, and c used in the quadratic formula. Do not solve.

  1. x2x+4=0
  2. x2+5x14=0
  3. x25=0
  4. 6x2+x=0
Answer

1. a=1,b=1, and c=4

3. a=1,b=0, and c=5

Exercise 9.E.6 quadratic formula

Use the quadratic formula to solve the following.

  1. x26x+6=0
  2. x2+10x+23=0
  3. 3y2y1=0
  4. 2y23y+5=0
  5. 5x236=0
  6. 7x2+2x=0
  7. x2+5x+1=0
  8. 4x22x+1=0
  9. t212t288=0
  10. t244t+484=0
  11. (x3)22x=47
  12. 9x(x+1)5=3x
Answer

1. 3±3

3. 1±136

5. ±655

7. 5±292

9. 12,24

11. 4±36

Exercise 9.E.7 Guidelines for Solving Quadratic Equations and Applications

Use the discriminant to determine the number and type of solutions.

  1. x2+5x+1=0
  2. x2+x1=0
  3. 4x24x+1=0
  4. 9x24=0
Answer

1. Two real solutions

3. One real solution

Exercise 9.E.8 Guidelines for Solving Quadratic Equations and Applications

Solve using any method.

  1. x2+4x60=0
  2. 9x2+7x=0
  3. 25t21=0
  4. t2+16=0
  5. x2x3=0
  6. 9x2+12x+1=0
  7. 4(x1)227=0
  8. (3x+5)24=0
  9. (x2)(x+3)=6
  10. x(x5)=12
  11. (x+1)(x8)+28=3x
  12. (9x2)(x+4)=28x9
Answer

1. 10,6

3. ±15

5. 1±132

7. 1±332

9. 4,3

11. 5±5

Exercise 9.E.9 Guidelines for Solving Quadratic Equations and Applications

Set up an algebraic equation and use it to solve the following.

  1. The length of a rectangle is 2 inches less than twice the width. If the area measures 25 square inches, then find the dimensions of the rectangle. Round off to the nearest hundredth.
  2. An 18-foot ladder leaning against a building reaches a height of 17 feet. How far is the base of the ladder from the wall? Round to the nearest tenth of a foot.
  3. The value in dollars of a new car is modeled by the function V(t)=125t23,000t+22,000, where t represents the number of years since it was purchased. Determine the age of the car when its value is $22,000.
  4. The height in feet reached by a baseball tossed upward at a speed of 48 feet/second from the ground is given by the function h(t)=16t2+48t, where t represents time in seconds. At what time will the baseball reach a height of 16 feet?
Answer

1. Length: 6.14 inches; width: 4.07 inches

3. It is worth $22,000 new and when it is 24 years old.

Exercise 9.E.10 graphing parabolas

Determine the x- and y-intercepts.

  1. y=2x2+5x3
  2. y=x212
  3. y=5x2x+2
  4. y=x2+10x25
Answer

1. x-intercepts: (3,0),(12,0); y-intercept: (0,3)

3. x-intercepts: none; y-intercept: (0,2)

Exercise 9.E.11 graphing parabolas

Find the vertex and the line of symmetry.

  1. y=x26x+1
  2. y=x2+8x1
  3. y=x2+3x1
  4. y=9x21
Answer

1. Vertex: (3,8); line of symmetry: x=3

3. Vertex: (32,134); line of symmetry: x=32

Exercise 9.E.12 graphing parabolas

Graph. Find the vertex and the y-intercept. In addition, find the x-intercepts if they exist.

  1. y=x2+8x+12
  2. y=x26x+7
  3. y=2x24
  4. y=x2+4x
  5. y=4x24x+1
  6. y=2x2
  7. y=2x2+8x7
  8. y=3x21
Answer

1.

Screenshot (276).png
Figure 9.E.1

3.

Screenshot (277).png
Figure 9.E.2

5.

Screenshot (278).png
Figure 9.E.3

7.

Screenshot (279).png
Figure 9.E.4
Exercise 9.E.13 graphing parabolas

Determine the maximum or minimum y-value.

  1. y=x210x+1
  2. y=x2+12x1
  3. y=5x2+6x
  4. y=2x2x1
  5. The value in dollars of a new car is modeled by the function V(t)=125t23,000t+22,000, where t represents the number of years since it was purchased. Determine the age of the car when its value is at a minimum.
  6. The height in feet reached by a baseball tossed upward at a speed of 48 feet/second from the ground is given by the function h(t)=16t2+48t, where t represents time in seconds. What is the maximum height of the baseball?
Answer

1. Minimum: y=24

3. Maximum: y=95

5. The car will have a minimum value 12 years after it is purchased.

Exercise 9.E.14 introduction to complex numbers and complex solutions

Rewrite in terms of i.

  1. 36
  2. 40
  3. 825
  4. -19
Answer

1. 6i

3. 22i5

Exercise 9.E.15 introduction to complex numbers and complex solutions

Perform the operations.

  1. (25i)+(3+4i)
  2. (67i)(123i)
  3. (23i)(5+i)
  4. 4i23i
Answer

1. 5i

3. 1313i

Exercise 9.E.16 introduction to complex numbers and complex solutions

Solve.

  1. 9x2+25=0
  2. 3x2+1=0
  3. y2y+5=0
  4. y2+2y+4
  5. 4x(x+2)+5=8x
  6. 2(x+2)(x+3)=3(x2+13)
Answer

1. ±33

3. 12±i192

5. ±i52

Sample Exam

Exercise 9.E.17

Solve by extracting the roots.

  1. 4x29=0
  2. (4x+1)25=0
Answer

1. ±32

Exercise 9.E.18

Solve by completing the square.

  1. x2+10x+19=0
  2. x2x1=0
Answer

1. 5±6

Exercise 9.E.19

Solve using the quadratic formula.

  1. 2x2+x+3=0
  2. x2+6x31=0
Answer

1. 1,32

Exercise 9.E.20

Solve using any method.

  1. (5x+1)(x+1)=1
  2. (x+5)(x5)=65
  3. x(x+3)=2
  4. 2(x2)26=3x2
Answer

1. 65,0

3. 2,1

Exercise 9.E.21

Set up an algebraic equation and solve.

  1. The length of a rectangle is twice its width. If the diagonal measures 65 centimeters, then find the dimensions of the rectangle.
  2. The height in feet reached by a model rocket launched from a platform is given by the function h(t)=16t2+256t+3, where t represents time in seconds after launch. At what time will the rocket reach 451 feet?
Answer

1. Length: 12 centimeters; width: 6 centimeters

Exercise 9.E.22

Graph. Find the vertex and the y-intercept. In addition, find the x-intercepts if they exist.

  1. y=2x24x6
  2. y=x2+4x4
  3. y=4x29
  4. y=x2+2x1
  5. Determine the maximum or minimum y-value: y=3x2+12x15.
  6. Determine the x- and y-intercepts: y=x2+x+4.
  7. Determine the domain and range: y=25x210x+1.
  8. The height in feet reached by a model rocket launched from a platform is given by the function h(t)=16t2+256t+3, where t represents time in seconds after launch. What is the maximum height attained by the rocket.
  9. A bicycle manufacturing company has determined that the weekly revenue in dollars can be modeled by the formula R=200nn2, where n represents the number of bicycles produced and sold. How many bicycles does the company have to produce and sell in order to maximize revenue?
  10. Rewrite in terms of i: 60.
  11. Divide: 42i4+2i.
Answer

1.

Screenshot (280).png
Figure 9.E.5

3.

Screenshot (281).png
Figure 9.E.6

5. Maximum: y=3

7. Domain: R; range: [0,)

9. To maximize revenue, the company needs to produce and sell 100 bicycles a week.

11. 35i45

Exercise 9.E.23

Solve.

  1. 25x2+3=0
  2. 2x2+5x1=0
Answer

2. 5±174


This page titled 9.E: Review Exercises and Sample Exam is shared under a not declared license and was authored, remixed, and/or curated by Anonymous via source content that was edited to the style and standards of the LibreTexts platform.

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