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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

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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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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