<< Chapter < Page Chapter >> Page >

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.

Got questions? Get instant answers now!

Writing exercises

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

Answers will vary.

Got questions? Get instant answers now!

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

Got questions? Get instant answers now!

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

Got questions? Get instant answers now!

r 2 + 32 = 0

no solution

Got questions? Get instant answers now!

4 3 v 2 + 4 = 28

v = ± 3 2

Got questions? Get instant answers now!

5 c 2 + 3 = 19

c = ± 4 5 5

Got questions? Get instant answers now!

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

( p 5 ) 2 + 3 = 19

p = 1 , 9

Got questions? Get instant answers now!

( u + 1 ) 2 = 45

u = −1 ± 3 5

Got questions? Get instant answers now!

( x 1 4 ) 2 = 3 16

x = 1 4 ± 3 4

Got questions? Get instant answers now!

( m 7 ) 2 + 6 = 30

m = 7 ± 2 6

Got questions? Get instant answers now!

( n 4 ) 2 50 = 150

Got questions? Get instant answers now!

( 5 c + 3 ) 2 = −20

no solution

Got questions? Get instant answers now!

m 2 6 m + 9 = 48

m = 3 ± 4 3

Got questions? Get instant answers now!

64 a 2 + 48 a + 9 = 81

a = 3 2 , 3 4

Got questions? Get instant answers now!

4 b 2 28 b + 49 = 25

Got questions? Get instant answers now!

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

Got questions? Get instant answers now!

a 2 3 a

( a 3 2 ) 2

Got questions? Get instant answers now!

p 2 + 4 5 p

( p + 2 5 ) 2

Got questions? Get instant answers now!

In the following exercises, solve by completing the square.

c 2 + 20 c = 21

c = 1 , −21

Got questions? Get instant answers now!

x 2 4 x = 32

x = −4 , 8

Got questions? Get instant answers now!

r 2 + 6 r = −100

no solution

Got questions? Get instant answers now!

v 2 14 v = −31

v = 7 ± 3 2

Got questions? Get instant answers now!

m 2 + 10 m 4 = −13

m = −9 , −1

Got questions? Get instant answers now!

a 2 = 3 a + 8

a = 3 2 ± 41 2

Got questions? Get instant answers now!

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

u = −6 ± 2 2

Got questions? Get instant answers now!

( z 10 ) ( z + 2 ) = 28

Got questions? Get instant answers now!

3 p 2 18 p + 15 = 15

p = 0 , 6

Got questions? Get instant answers now!

4 y 2 6 y = 4

y = 1 2 , 2

Got questions? Get instant answers now!

3 c 2 + 2 c = 9

c = 1 3 ± 2 7 3

Got questions? Get instant answers now!

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

Got questions? Get instant answers now!

r 2 r 42 = 0

r = −6 , 7

Got questions? Get instant answers now!

4 v 2 + v 5 = 0

v = 5 4 , 1

Got questions? Get instant answers now!

3 m 2 + 8 m + 2 = 0

m = −4 ± 10 3

Got questions? Get instant answers now!

6 a 2 5 a + 2 = 0

no real solution

Got questions? Get instant answers now!

u ( u 10 ) + 3 = 0

u = 5 ± 22

Got questions? Get instant answers now!

1 8 p 2 1 5 p = 1 20

p = 4 ± 6 5

Got questions? Get instant answers now!

4 c 2 + 4 c + 1 = 0

c = 1 2

Got questions? Get instant answers now!

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

Got questions? Get instant answers now!
  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
Got questions? Get instant answers now!

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

Got questions? Get instant answers now!
  1. 4 d 2 + 10 d 5 = 21
  2. 25 x 2 60 x + 36 = 0
  3. 6 ( 5 v 7 ) 2 = 150
Got questions? Get instant answers now!

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 .

Got questions? Get instant answers now!

Questions & Answers

how did you get 1640
Noor Reply
If auger is pair are the roots of equation x2+5x-3=0
Peter Reply
Wayne and Dennis like to ride the bike path from Riverside Park to the beach. Dennis’s speed is seven miles per hour faster than Wayne’s speed, so it takes Wayne 2 hours to ride to the beach while it takes Dennis 1.5 hours for the ride. Find the speed of both bikers.
MATTHEW Reply
420
Sharon
from theory: distance [miles] = speed [mph] × time [hours] info #1 speed_Dennis × 1.5 = speed_Wayne × 2 => speed_Wayne = 0.75 × speed_Dennis (i) info #2 speed_Dennis = speed_Wayne + 7 [mph] (ii) use (i) in (ii) => [...] speed_Dennis = 28 mph speed_Wayne = 21 mph
George
Let W be Wayne's speed in miles per hour and D be Dennis's speed in miles per hour. We know that W + 7 = D and W * 2 = D * 1.5. Substituting the first equation into the second: W * 2 = (W + 7) * 1.5 W * 2 = W * 1.5 + 7 * 1.5 0.5 * W = 7 * 1.5 W = 7 * 3 or 21 W is 21 D = W + 7 D = 21 + 7 D = 28
Salma
Devon is 32 32​​ years older than his son, Milan. The sum of both their ages is 54 54​. Using the variables d d​ and m m​ to represent the ages of Devon and Milan, respectively, write a system of equations to describe this situation. Enter the equations below, separated by a comma.
Aaron Reply
find product (-6m+6) ( 3m²+4m-3)
SIMRAN Reply
-42m²+60m-18
Salma
what is the solution
bill
how did you arrive at this answer?
bill
-24m+3+3mÁ^2
Susan
i really want to learn
Amira
I only got 42 the rest i don't know how to solve it. Please i need help from anyone to help me improve my solving mathematics please
Amira
Hw did u arrive to this answer.
Aphelele
hi
Bajemah
-6m(3mA²+4m-3)+6(3mA²+4m-3) =-18m²A²-24m²+18m+18mA²+24m-18 Rearrange like items -18m²A²-24m²+42m+18A²-18
Salma
complete the table of valuesfor each given equatio then graph. 1.x+2y=3
Jovelyn Reply
x=3-2y
Salma
y=x+3/2
Salma
Hi
Enock
given that (7x-5):(2+4x)=8:7find the value of x
Nandala
3x-12y=18
Kelvin
please why isn't that the 0is in ten thousand place
Grace Reply
please why is it that the 0is in the place of ten thousand
Grace
Send the example to me here and let me see
Stephen
A meditation garden is in the shape of a right triangle, with one leg 7 feet. The length of the hypotenuse is one more than the length of one of the other legs. Find the lengths of the hypotenuse and the other leg
Marry Reply
how far
Abubakar
cool u
Enock
state in which quadrant or on which axis each of the following angles given measure. in standard position would lie 89°
Abegail Reply
hello
BenJay
hi
Method
I am eliacin, I need your help in maths
Rood
how can I help
Sir
hmm can we speak here?
Amoon
however, may I ask you some questions about Algarba?
Amoon
hi
Enock
what the last part of the problem mean?
Roger
The Jones family took a 15 mile canoe ride down the Indian River in three hours. After lunch, the return trip back up the river took five hours. Find the rate, in mph, of the canoe in still water and the rate of the current.
cameron Reply
Shakir works at a computer store. His weekly pay will be either a fixed amount, $925, or $500 plus 12% of his total sales. How much should his total sales be for his variable pay option to exceed the fixed amount of $925.
mahnoor Reply
I'm guessing, but it's somewhere around $4335.00 I think
Lewis
12% of sales will need to exceed 925 - 500, or 425 to exceed fixed amount option. What amount of sales does that equal? 425 ÷ (12÷100) = 3541.67. So the answer is sales greater than 3541.67. Check: Sales = 3542 Commission 12%=425.04 Pay = 500 + 425.04 = 925.04. 925.04 > 925.00
Munster
difference between rational and irrational numbers
Arundhati Reply
When traveling to Great Britain, Bethany exchanged $602 US dollars into £515 British pounds. How many pounds did she receive for each US dollar?
Jakoiya Reply
how to reduced echelon form
Solomon Reply
Jazmine trained for 3 hours on Saturday. She ran 8 miles and then biked 24 miles. Her biking speed is 4 mph faster than her running speed. What is her running speed?
Zack Reply
d=r×t the equation would be 8/r+24/r+4=3 worked out
Sheirtina
Practice Key Terms 6

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Elementary algebra. OpenStax CNX. Jan 18, 2017 Download for free at http://cnx.org/content/col12116/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Elementary algebra' conversation and receive update notifications?

Ask