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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

Ayele, K., 2003. Introductory Economics, 3rd ed., Addis Ababa.
Widad Reply
can you send the book attached ?
Ariel
?
Ariel
What is economics
Widad Reply
the study of how humans make choices under conditions of scarcity
AI-Robot
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn Reply
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn
what is ecnomics
Jan Reply
this is the study of how the society manages it's scarce resources
Belonwu
what is macroeconomic
John Reply
macroeconomic is the branch of economics which studies actions, scale, activities and behaviour of the aggregate economy as a whole.
husaini
etc
husaini
difference between firm and industry
husaini Reply
what's the difference between a firm and an industry
Abdul
firm is the unit which transform inputs to output where as industry contain combination of firms with similar production 😅😅
Abdulraufu
Suppose the demand function that a firm faces shifted from Qd  120 3P to Qd  90  3P and the supply function has shifted from QS  20  2P to QS 10  2P . a) Find the effect of this change on price and quantity. b) Which of the changes in demand and supply is higher?
Toofiq Reply
explain standard reason why economic is a science
innocent Reply
factors influencing supply
Petrus Reply
what is economic.
Milan Reply
scares means__________________ends resources. unlimited
Jan
economics is a science that studies human behaviour as a relationship b/w ends and scares means which have alternative uses
Jan
calculate the profit maximizing for demand and supply
Zarshad Reply
Why qualify 28 supplies
Milan
what are explicit costs
Nomsa Reply
out-of-pocket costs for a firm, for example, payments for wages and salaries, rent, or materials
AI-Robot
concepts of supply in microeconomics
David Reply
economic overview notes
Amahle Reply
identify a demand and a supply curve
Salome Reply
i don't know
Parul
there's a difference
Aryan
Demand curve shows that how supply and others conditions affect on demand of a particular thing and what percent demand increase whith increase of supply of goods
Israr
Hi Sir please how do u calculate Cross elastic demand and income elastic demand?
Abari
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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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