<< 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

summarize halerambos & holbon
David Reply
the Three stages of Auguste Comte
Clementina Reply
what are agents of socialization
Antonio Reply
sociology of education
Nuhu Reply
definition of sociology of education
Nuhu
what is culture
Abdulrahim Reply
shared beliefs, values, and practices
AI-Robot
What are the two type of scientific method
ogunniran Reply
I'm willing to join you
Aceng Reply
what are the scientific method of sociology
Man
what is socialization
ogunniran Reply
the process wherein people come to understand societal norms and expectations, to accept society's beliefs, and to be aware of societal values
AI-Robot
scientific method in doing research
ogunniran
defimition of sickness in afica
Anita
Cosmology
ogunniran
Hmmm
ogunniran
list and explain the terms that found in society
REMMY Reply
list and explain the terms that found in society
Mukhtar
what are the agents of socialization
Antonio
Family Peer group Institution
Abdulwajud
I mean the definition
Antonio
ways of perceived deviance indifferent society
Naomi Reply
reasons of joining groups
SAM
to bring development to the nation at large
Hyellafiya
entails of consultative and consensus building from others
Gadama
World first Sociologist?
Abu
What is evolutionary model
Muhammad Reply
Evolution models refer to mathematical and computational representations of the processes involved in biological evolution. These models aim to simulate and understand how species change over time through mechanisms such as natural selection, genetic drift, and mutation. Evolutionary models can be u
faruk
what are the modern trends in religious behaviours
Selekeye Reply
what are social norms
Daniel Reply
shared standards of acceptable behavior by the group or appropriate behavior in a particular institution or those behaviors that are acceptable in a society
Lucius
that is how i understood it
Lucius
examples of societal norms
Diamond
Discuss the characteristics of the research located within positivist and the interpretivist paradigm
Tariro Reply
what is Industrialisation
Selekeye Reply
industrialization
Angelo
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