<< Chapter < Page Chapter >> Page >
This module is from Elementary Algebra by Denny Burzynski and Wade Ellis, Jr. The distinction between the principal square root of the number x and the secondary square root of the number x is made by explanation and by example. The simplification of the radical expressions that both involve and do not involve fractions is shown in many detailed examples; this is followed by an explanation of how and why radicals are eliminated from the denominator of a radical expression. Real-life applications of radical equations have been included, such as problems involving daily output, daily sales, electronic resonance frequency, and kinetic energy.Objectives of this module: understand the process used in adding and subtracting square roots, be able to add and subtract square roots.

Overview

  • The Logic Behind The Process
  • The Process

The logic behind the process

Now we will study methods of simplifying radical expressions such as

4 3 + 8 3 or 5 2 x 11 2 x + 4 ( 2 x + 1 )

The procedure for adding and subtracting square root expressions will become apparent if we think back to the procedure we used for simplifying polynomial expressions such as

4 x + 8 x or 5 a 11 a + 4 ( a + 1 )

The variables x and a are letters representing some unknown quantities (perhaps x represents 3 and a represents 2 x ). Combining like terms gives us

4 x + 8 x = 12 x or 4 3 + 8 3 = 12 3 and 5 a - 11 a + 4 ( a + 1 ) or 5 2 x - 11 2 x + 4 ( 2 x + 1 ) 5 a - 11 a + 4 a + 4 5 2 x - 11 2 x + 4 2 x + 4 - 2 a + 4 - 2 2 x + 4

The process

Let’s consider the expression 4 3 + 8 3 . There are two ways to look at the simplification process:

  1. We are asking, “How many square roots of 3 do we have?”

    4 3 means we have 4 “square roots of 3”

    8 3 means we have 8 “square roots of 3”

    Thus, altogether we have 12 “square roots of 3.”
  2. We can also use the idea of combining like terms. If we recall, the process of combining like terms is based on the distributive property

    4 x + 8 x = 12 x because 4 x + 8 x = ( 4 + 8 ) x = 12 x

    We could simplify 4 3 + 8 3 using the distributive property.

    4 3 + 8 3 = ( 4 + 8 ) 3 = 12 3

Both methods will give us the same result. The first method is probably a bit quicker, but keep in mind, however, that the process works because it is based on one of the basic rules of algebra, the distributive property of real numbers.

Sample set a

Simplify the following radical expressions.

4 32 + 5 2 . Simplify 32 . 4 16 · 2 + 5 2 = 4 16 2 + 5 2 = 4 · 4 2 + 5 2 = 16 2 + 5 2 = 21 2

Got questions? Get instant answers now!

- 3 x 75 + 2 x 48 - x 27 . Simple each of the three radicals . = - 3 x 25 · 3 + 2 x 16 · 3 - x 9 · 3 = - 15 x 3 + 8 x 3 - 3 x 3 = ( - 15 x + 8 x - 3 x ) 3 = - 10 x 3

Got questions? Get instant answers now!

5 a 24 a 3 - 7 54 a 5 + a 2 6 a + 6 a . Simplify each radical . = 5 a 4 · 6 · a 2 · a - 7 9 · 6 · a 4 · a + a 2 6 a + 6 a = 10 a 2 6 a - 21 a 2 6 a + a 2 6 a + 6 a = ( 10 a 2 - 21 a 2 + a 2 ) 6 a + 6 a = - 10 a 2 6 a + 6 a Factor out - 2 a . (This step is optional .) = - 2 a ( 5 a 6 a - 3 )

Got questions? Get instant answers now!

Practice set a

Find each sum or difference.

7 84 x 12 189 x + 2 21 x

48 21 x

Got questions? Get instant answers now!

4 x 54 x 3 + 36 x 2 + 3 24 x 5 3 x

18 x 2 6 x + 3 x

Got questions? Get instant answers now!

Sample set b

3 + 8 3 8 . We'll rationalize the denominator by multiplying this fraction by 1 in the form 3 + 8 3 + 8 . 3 + 8 3 8 · 3 + 8 3 + 8 = ( 3 + 8 ) ( 3 + 8 ) 3 2 ( 8 ) 2 = 9 + 3 8 + 3 8 + 8 8 9 8 = 9 + 6 8 + 8 1 = 17 + 6 8 = 17 + 6 4 · 2 = 17 + 12 2

Got questions? Get instant answers now!

2 + 7 4 - 3 . Rationalize the denominator by multiplying this fraction by 1 in the from 4 + 3 4 + 3 . 2 + 7 4 - 3 · 4 + 3 4 + 3 = ( 2 + 7 ) ( 4 + 3 ) 4 2 - ( 3 ) 2 = 8 + 2 3 + 4 7 + 21 16 - 3 = 8 + 2 3 + 4 7 + 21 13

Got questions? Get instant answers now!

Practice set b

Simplify each by performing the indicated operation.

5 ( 6 4 )

30 4 5

Got questions? Get instant answers now!

( 5 + 7 ) ( 2 + 8 )

3 10 + 3 14

Got questions? Get instant answers now!

( 3 2 2 3 ) ( 4 3 + 8 )

8 6 12

Got questions? Get instant answers now!

4 + 5 3 8

12 + 8 2 + 3 5 + 2 10

Got questions? Get instant answers now!

Exercises

For the following problems, simplify each expression by performing the indicated operation.

3 6 12 6

15 6

Got questions? Get instant answers now!

6 40 + 8 80

12 10 + 32 5

Got questions? Get instant answers now!

5 x y 2 x y 3 3 y 2 2 x 3 y

2 x y 2 2 x y

Got questions? Get instant answers now!

24 2 54 4 12

4 6 8 3

Got questions? Get instant answers now!

8 20 9 125 + 10 180

5

Got questions? Get instant answers now!

14 + 2 56 3 136

5 14 6 34

Got questions? Get instant answers now!

4 a x 3 x + 2 3 a 2 x 3 + 7 3 a 2 x 3

13 a x 3 x

Got questions? Get instant answers now!

3 b y 5 y + 4 5 b 2 y 3 2 5 b 2 y 3

Got questions? Get instant answers now!

( 1 + 3 ) ( 2 3 )

1 + 3

Got questions? Get instant answers now!

( 3 2 ) ( 4 2 )

7 ( 2 2 )

Got questions? Get instant answers now!

( 2 + 5 ) ( 2 + 3 5 )

17 + 4 10

Got questions? Get instant answers now!

( 2 6 3 ) ( 3 6 + 2 3 )

Got questions? Get instant answers now!

( 4 5 2 3 ) ( 3 5 + 3 )

54 2 15

Got questions? Get instant answers now!

( 3 8 2 2 ) ( 4 2 5 8 )

Got questions? Get instant answers now!

( 12 + 5 3 ) ( 2 3 2 12 )

42

Got questions? Get instant answers now!

( 2 7 ) 2

11 4 7

Got questions? Get instant answers now!

( 2 + 5 x ) 2

4 + 4 5 x + 5 x

Got questions? Get instant answers now!

( 8 6 b ) 2

64 16 6 b + 6 b

Got questions? Get instant answers now!

( 3 y 7 y ) 2

9 y 2 6 y 7 y + 7 y

Got questions? Get instant answers now!

( 2 + 5 ) ( 2 5 )

1

Got questions? Get instant answers now!

( 6 + 7 ) ( 6 7 )

29

Got questions? Get instant answers now!

( x + y ) ( x y )

x y

Got questions? Get instant answers now!

4 6 + 2

2 ( 6 2 ) 17

Got questions? Get instant answers now!

4 + 5 4 5

21 + 8 5 11

Got questions? Get instant answers now!

8 3 2 + 18

16 + 2 3 + 24 2 3 6 14

Got questions? Get instant answers now!

2 b 3 b 3 b + 2 b

2 6 5

Got questions? Get instant answers now!

Exercises for review

( [link] ) Simplify ( x 5 y 3 x 2 y ) 5 .

Got questions? Get instant answers now!

( [link] ) Simplify ( 8 x 3 y ) 2 ( x 2 y 3 ) 4 .

64 x 14 y 14

Got questions? Get instant answers now!

( [link] ) Write ( x 1 ) 4 ( x 1 ) 7 so that only positive exponents appear.

Got questions? Get instant answers now!

( [link] ) Simplify 27 x 5 y 10 z 3 .

3 x 2 y 5 z 3 x z

Got questions? Get instant answers now!

( [link] ) Simplify 1 2 + x by rationalizing the denominator.

Got questions? Get instant answers now!

Questions & Answers

what is cell
Oppicial Reply
To know how bones are functions
DAUDA Reply
diagram of the heart
Victoria Reply
what are the layers of the muscles
Tongdock Reply
What is Amebae
Najibu Reply
the collection of fluids in the throat is cause by what
Emmanuel Reply
what is difference between meiosis and mitosis
Aishetu Reply
what is difference between mitosis and meiosis
Aishetu
What is Anatomy
Najibu Reply
What the difference between the Anatomy and physiology
Najibu
What is the meaning of chromoprotein
Aisha Reply
what is cartilage
Abdulkadir Reply
tough , white fibrous tissue
Henry
distinguish between anatomy and physiology
Amina Reply
Anatomy is the study of internal structure of an organism while physiology is the study of the function/relationship of the body organs working together as a system in an organism.
adeyeye
distinguish between anatomy and physiology
Erny Reply
regional anatomy is the study of the body regionally
Ismail Reply
what is the meaning of regional anatomy
Aminat Reply
epithelial tissue: it covers the Hollow organs and body cavities
Esomchi Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

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. May 08, 2009 Download for free at http://cnx.org/content/col10614/1.3
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