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This module is from Elementary Algebra</link>by Denny Burzynski and Wade Ellis, Jr. Methods of solving quadratic equations as well as the logic underlying each method are discussed. Factoring, extraction of roots, completing the square, and the quadratic formula are carefully developed. The zero-factor property of real numbers is reintroduced. The chapter also includes graphs of quadratic equations based on the standard parabola, y = x^2, and applied problems from the areas of manufacturing, population, physics, geometry, mathematics (numbers and volumes), and astronomy, which are solved using the five-step method.This module contains an exercise supplement for the chapter "Quadratic Equations".

Exercise supplement

Solving quadratic equations ( [link] ) - solving quadratic equations by factoring ( [link] )

For the following problems, solve the equations.

( x 2 ) ( x 5 ) = 0

x = 2 , 5

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( b + 1 ) ( b 6 ) = 0

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( a + 10 ) ( a 5 ) = 0

a = 10 , 5

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( y 3 ) ( y 4 ) = 0

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( m 8 ) ( m + 1 ) = 0

m = 8 , 1

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( 4 y + 1 ) ( 2 y + 3 ) = 0

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( x + 2 ) ( 3 x 1 ) = 0

x = 2 , 1 3

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( 5 a 2 ) ( 3 a 10 ) = 0

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x ( 2 x + 3 ) = 0

x = 0 , 3 2

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( y + 3 ) 2 = 0

y = 3

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16 y 2 49 = 0

y = ± 7 4

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a 2 + 6 a + 8 = 0

a = 4 , 2

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s 2 9 s + 8 = 0

s = 1 , 8

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11 y 2 = 6 y 2

y = 1 6 , 2

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3 ( y 2 8 ) = 7 y

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a ( 4 b + 7 ) = 0

a = 0 ; b = 7 4

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5 a 2 125 = 0

a = ± 5

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m 2 6 m + 5 = 0

m = 5 , 1

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x 2 + 3 x = 28

x = 7 , 4

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2 y 2 6 y = 8

y = 4 , 1

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2 r 2 = 5 3 r

r = 5 2 , 1

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Solving quadratic equations using the method of extraction of roots ( [link] )

For the following problems, solve the equations using extraction of roots.

s 2 10 = 0

s = ± 10

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3 y 2 = 75

y = ± 5

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Solve y 2 = 4 a 2 for y .

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Solve m 2 = 16 n 2 p 4 for m .

m = ± 4 n p 2

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Solve x 2 = 25 y 4 z 10 w 8 for x .

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Solve x 2 y 2 = 0 for y .

y = ± x

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Solve a 4 b 8 x 6 y 12 z 2 = 0 for a 2 .

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( x 2 ) 2 = 9

x = 5 , 1

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( a + 10 ) 2 = 1

a = 11 , 9

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( r 8 ) 2 = 10

r = 8 ± 10

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( a 2 ) 2 = 2

No real number solution.

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Solve ( x 2 b ) 2 = b 2 for x

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Solve ( y + 6 ) 2 = a for y .

y = 6 ± a

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Solve ( 2 a 5 ) 2 = c for a .

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Solve ( 3 m 11 ) 2 = 2 a 2 for m .

m = 11 ± a 2 3

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Solving quadratic equations using the method of completing the square ( [link] ) - solving quadratic equations using the quadratic formula ( [link] )

For the following problems, solve the equations by completing the square or by using the quadratic formula.

s 2 + 2 s 24 = 0

s = 4 , 6

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b 2 + b 8 = 0

b = 1 ± 33 2

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5 a 2 + 2 a 6 = 0

a = 1 ± 31 5

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y 2 = 2 y + 1

y = 1 ± 2

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r 2 + 2 r = 9

r = 1 ± 10

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10 x 3 + 2 x 2 22 x = 0

x = 0 , 1 ± 221 10

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6 r 3 + 6 r 2 3 r = 0

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15 x 2 + 2 x 3 = 12 x 4

x = 0 , 1 ± 181 12

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6 x 3 6 x = 6 x 2

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( x + 3 ) ( x 4 ) = 3

x = 1 ± 61 2

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( y 1 ) ( y 2 ) = 6

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( a + 3 ) ( a + 4 ) = 10

No real number solution.

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( 2 m + 1 ) ( 3 m 1 ) = 2

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( 5 r + 6 ) ( r 1 ) = 2

r = 1 ± 161 10

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4 x 2 + 2 x 3 = 3 x 2 + x + 1

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5 a 2 + 5 a + 4 = 3 a 2 + 2 a + 5

a = 3 ± 17 4

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( r 8 ) 2 = 70

r = 8 ± 70

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Applications ( [link] )

For the following problems, find the solution.

The revenue R , in dollars, collected by a certain manufacturer of inner tubes is related to the number x of inner tubes sold by R = 1400 16 x + 3 x 2 . How many inner tubes must be sold to produce a profit of $1361?

No solution.

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A study of the air quality in a particular city by an environmental group suggests that t years from now the level of carbon monoxide, in parts per million, in the air will be A = 0.8 t 2 + 0.5 t + 3.3.
(a) What is the level, in parts per million, of carbon monoxide in the air now?
(b) How many years from now will the carbon monoxide level be at 6 parts per million?

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A contractor is to pour a concrete walkway around a community garden that is 15 feet wide and 50 feet long. The area of the walkway and garden is to be 924 square feet and of uniform width. How wide should the contractor make it?

x 1.29 feet

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A ball thrown vertically into the air has the equation of motion h = 144 + 48 t 16 t 2
(a) How high is the ball at t = 0 ?
(b) How high is the ball at t = 1 ?
(c) When does the ball hit the ground?

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The length of a rectangle is 5 feet longer than three times its width. Find the dimensions if the area is to be 138 square feet.

w = 6

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The area of a triangle is 28 square centimeters. The base is 3 cm longer than the height. Find both the length of the base and the height.

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The product of two consecutive integers is 210. Find them.

x = 15 , 14 , or 14 , 15

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The product of two consecutive negative integers is 272. Find them.

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A box with no top and a square base is to be made by cutting out 3-inch squares from each corner and folding up the sides of a piece of cardboard. The volume of the box is to be 25 cubic inches. What size should the piece of cardboard be?

x = 18 + 5 3 3

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Questions & Answers

it is the relatively stable flow of income
Chidubem Reply
what is circular flow of income
Divine Reply
branches of macroeconomics
SHEDRACK Reply
what is Flexible exchang rate?
poudel Reply
is gdp a reliable measurement of wealth
Atega Reply
introduction to econometrics
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Tom
Why is unemployment rate never zero at full employment?
Priyanka Reply
bcoz of existence of frictional unemployment in our economy.
Umashankar
what is flexible exchang rate?
poudel
due to existence of the pple with disabilities
Abdulraufu
the demand of a good rises, causing the demand for another good to fall
Rushawn Reply
is it possible to leave every good at the same level
Joseph
I don't think so. because check it, if the demand for chicken increases, people will no longer consume fish like they used to causing a fall in the demand for fish
Anuolu
is not really possible to let the value of a goods to be same at the same time.....
Salome
Suppose the inflation rate is 6%, does it mean that all the goods you purchase will cost 6% more than previous year? Provide with reasoning.
Geetha Reply
Not necessarily. To measure the inflation rate economists normally use an averaged price index of a basket of certain goods. So if you purchase goods included in the basket, you will notice that you pay 6% more, otherwise not necessarily.
Waeth
discus major problems of macroeconomics
Alii Reply
what is the problem of macroeconomics
Yoal
Economic growth Stable prices and low unemployment
Ephraim
explain inflationcause and itis degre
Miresa Reply
what is inflation
Getu
increase in general price levels
WEETO
Good day How do I calculate this question: C= 100+5yd G= 2000 T= 2000 I(planned)=200. Suppose the actual output is 3000. What is the level of planned expenditures at this level of output?
Chisomo Reply
how to calculate actual output?
Chisomo
how to calculate the equilibrium income
Beshir
Criteria for determining money supply
Thapase Reply
who we can define macroeconomics in one line
Muhammad
Aggregate demand
Mohammed
C=k100 +9y and i=k50.calculate the equilibrium level of output
Mercy Reply
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money as unit of account means what?
Kalombe
A unit of account is something that can be used to value goods and services and make calculations
Jim
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Muhammad
I want to know how can we define macroeconomics in one line
Muhammad
it must be .9 or 0.9 no Mpc is greater than 1 Y=100+.9Y+50 Y-.9Y=150 0.1Y/0.1=150/0.1 Y=1500
Kalombe
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Kalombe
hi can someone help me on this question If a negative shocks shifts the IS curve to the left, what type of policy do you suggest so as to stabilize the level of output? discuss your answer using appropriate graph.
Galge Reply
if interest rate is increased this will will reduce the level of income shifting the curve to the left ◀️
Kalombe
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Source:  OpenStax, Elementary algebra. OpenStax CNX. May 08, 2009 Download for free at http://cnx.org/content/col10614/1.3
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