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In the previous set of exercises, you worked with the quadratic equation R = x 2 + 100 x that modeled the revenue received from selling backpacks at a price of x dollars. You found the selling price that would give the maximum revenue and calculated the maximum revenue. Now you will look at more characteristics of this model.
Graph the equation R = x 2 + 100 x . Find the values of the x -intercepts.

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Writing exercises

For the revenue model in [link] and [link] , explain what the x -intercepts mean to the computer store owner.

Answers will vary.

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For the revenue model in [link] and [link] , explain what the x -intercepts mean to the backpack retailer.

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Self check

After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

This table has six rows and four columns. The first row is a header row and it labels each column. The first column is labeled

What does this checklist tell you about your mastery of this section? What steps will you take to improve?

10.1 Solve Quadratic Equations Using the Square Root Property

In the following exercises, solve using the Square Root Property.

m 2 40 = 0

m = ± 2 10

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r 2 + 32 = 0

no solution

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4 3 v 2 + 4 = 28

v = ± 3 2

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5 c 2 + 3 = 19

c = ± 4 5 5

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In the following exercises, solve using the Square Root Property.

( p 5 ) 2 + 3 = 19

p = 1 , 9

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( u + 1 ) 2 = 45

u = −1 ± 3 5

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( x 1 4 ) 2 = 3 16

x = 1 4 ± 3 4

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( m 7 ) 2 + 6 = 30

m = 7 ± 2 6

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( n 4 ) 2 50 = 150

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( 5 c + 3 ) 2 = −20

no solution

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m 2 6 m + 9 = 48

m = 3 ± 4 3

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64 a 2 + 48 a + 9 = 81

a = 3 2 , 3 4

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4 b 2 28 b + 49 = 25

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10.2 Solve Quadratic Equations Using Completing the Square

In the following exercises, complete the square to make a perfect square trinomial. Then write the result as a binomial squared.

m 2 8 m

( m 4 ) 2

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a 2 3 a

( a 3 2 ) 2

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p 2 + 4 5 p

( p + 2 5 ) 2

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In the following exercises, solve by completing the square.

c 2 + 20 c = 21

c = 1 , −21

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x 2 4 x = 32

x = −4 , 8

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r 2 + 6 r = −100

no solution

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v 2 14 v = −31

v = 7 ± 3 2

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m 2 + 10 m 4 = −13

m = −9 , −1

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a 2 = 3 a + 8

a = 3 2 ± 41 2

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( u + 8 ) ( u + 4 ) = 14

u = −6 ± 2 2

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( z 10 ) ( z + 2 ) = 28

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3 p 2 18 p + 15 = 15

p = 0 , 6

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4 y 2 6 y = 4

y = 1 2 , 2

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3 c 2 + 2 c = 9

c = 1 3 ± 2 7 3

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10.3 Solve Quadratic Equations Using the Quadratic Formula

In the following exercises, solve by using the Quadratic Formula.

4 x 2 5 x + 1 = 0

x = 1 4 , 1

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r 2 r 42 = 0

r = −6 , 7

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4 v 2 + v 5 = 0

v = 5 4 , 1

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3 m 2 + 8 m + 2 = 0

m = −4 ± 10 3

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6 a 2 5 a + 2 = 0

no real solution

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u ( u 10 ) + 3 = 0

u = 5 ± 22

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1 8 p 2 1 5 p = 1 20

p = 4 ± 6 5

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4 c 2 + 4 c + 1 = 0

c = 1 2

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In the following exercises, determine the number of solutions to each quadratic equation.

  1. 9 x 2 6 x + 1 = 0
  2. 3 y 2 8 y + 1 = 0
  3. 7 m 2 + 12 m + 4 = 0
  4. 5 n 2 n + 1 = 0

1 2 2 none

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  1. 5 x 2 7 x 8 = 0
  2. 7 x 2 10 x + 5 = 0
  3. 25 x 2 90 x + 81 = 0
  4. 15 x 2 8 x + 4 = 0
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In the following exercises, identify the most appropriate method (Factoring, Square Root, or Quadratic Formula) to use to solve each quadratic equation.

  1. 16 r 2 8 r + 1 = 0
  2. 5 t 2 8 t + 3 = 9
  3. 3 ( c + 2 ) 2 = 15

factor Quadratic Formula square root

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  1. 4 d 2 + 10 d 5 = 21
  2. 25 x 2 60 x + 36 = 0
  3. 6 ( 5 v 7 ) 2 = 150
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10.4 Solve Applications Modeled by Quadratic Equations

In the following exercises, solve by using methods of factoring, the square root principle, or the quadratic formula.

Find two consecutive odd numbers whose product is 323.

Two consecutive odd numbers whose product is 323 are 17 and 19, and −17 and −19 .

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Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Practice Key Terms 6

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Source:  OpenStax, Elementary algebra. OpenStax CNX. Jan 18, 2017 Download for free at http://cnx.org/content/col12116/1.2
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