<< Chapter < Page Chapter >> Page >

Solve 3 ( m 6 ) 2 m = 4 + 1 for m .

3 ( m 6 ) 2 m = 4 + 1 3 m 18 2 m = 3 m 18 = 3 m = 15

C h e c k : 3 ( 15 6 ) 2 ( 15 ) = 4 + 1 Is this correct? 3 ( 9 ) 30 = 3 Is this correct? 27 30 = 3 Is this correct? 3 = 3 Yes, this is correct .

Got questions? Get instant answers now!

Practice set b

Solve and check each equation.

16 x 3 15 x = 8 for x .

x = 11

Got questions? Get instant answers now!

4 ( y 5 ) 3 y = 1 for y .

y = 19

Got questions? Get instant answers now!

2 ( a 2 + 3 a 1 ) + 2 a 2 + 7 a = 0 for a .

a = 2

Got questions? Get instant answers now!

5 m ( m 2 a 1 ) 5 m 2 + 2 a ( 5 m + 3 ) = 10 for a .

a = 10 + 5 m 6

Got questions? Get instant answers now!

Often the variable we wish to solve for will appear on both sides of the equal sign. We can isolate the variable on either the left or right side of the equation by using the techniques of Sections [link] and [link] .

Sample set c

Solve 6 x 4 = 2 x + 8 for x .

6 x 4 = 2 x + 8 To isolate x on the left side, subtract 2 m from both sides . 6 x 4 2 x = 2 x + 8 2 x 4 x 4 = 8 Add 4 to both sides . 4 x 4 + 4 = 8 + 4 4 x = 12 Divide both sides by 4. 4 x 4 = 12 4 x = 3

C h e c k : 6 ( 3 ) 4 = 2 ( 3 ) + 8 Is this correct? 18 4 = 6 + 8 Is this correct? 14 = 14 Yes, this is correct .

Got questions? Get instant answers now!

Solve 6 ( 1 3 x ) + 1 = 2 x [ 3 ( x 7 ) 20 ] for x .

On left side of an equation, arrows show that six is multiplied with each term inside the parentheses, and on right side, arrows show that three is multiplied with each term inside the parentheses.

6 18 x + 1 = 2 x [ 3 x 21 20 ] 18 x + 7 = 2 x [ 3 x 41 ] 18 x + 7 = 2 x 3 x + 41 18 x + 7 = x + 41 To isolate x on the right side, add 18 x to both sides . 18 x + 7 + 18 x = x + 41 + 18 x 7 = 17 x + 41 Subtract 41 from both sides . 7 41 = 17 x + 41 41 34 = 17 x Divide both sides by 17. 34 17 = 17 x 17 2 = x Since the equation 2 = x is equivalent to the equation x = 2 , we can write the answer as x = 2. x = 2

C h e c k : 6 ( 1 3 ( 2 ) ) + 1 = 2 ( 2 ) [ 3 ( 2 7 ) 20 ] Is this correct? 6 ( 1 + 6 ) + 1 = 4 [ 3 ( 9 ) 20 ] Is this correct? 6 ( 7 ) + 1 = 4 [ 27 20 ] Is this correct? 42 + 1 = 4 [ 47 ] Is this correct? 43 = 4 + 47 Is this correct? 43 = 43 Yes, this is correct .

Got questions? Get instant answers now!

Practice set c

Solve 8 a + 5 = 3 a 5 for a .

a = 2

Got questions? Get instant answers now!

Solve 9 y + 3 ( y + 6 ) = 15 y + 21 for y .

y = 1

Got questions? Get instant answers now!

Solve 3 k + 2 [ 4 ( k 1 ) + 3 ] = 63 2 k for k .

k = 5

Got questions? Get instant answers now!

Recognizing identities and contradictions

As we noted in Section [link] , some equations are identities and some are contradictions. As the problems of Sample Set D will suggest,

    Recognizing an identity

  1. If, when solving an equation, all the variables are eliminated and a true statement results, the equation is an identity.

    Recognizing a contradiction

  1. If, when solving an equation, all the variables are eliminated and a false statement results, the equation is a contradiction.

Sample set d

Solve 9 x + 3 ( 4 3 x ) = 12 for x .

On left side of an equation, arrows show that three is multiplied with each term inside the parentheses.

9 x + 12 9 x = 12 12 = 12

The variable has been eliminated and the result is a true statement. The original equation is an identity.

Got questions? Get instant answers now!

Solve 2 ( 10 2 y ) 4 y + 1 = 18 for y .

On left side of an equation, arrows show that negative two is multiplied with each term inside the parentheses.

20 + 4 y 4 y + 1 = 18 19 = 18

The variable has been eliminated and the result is a false statement. The original equation is a contradiction.

Got questions? Get instant answers now!

Practice set d

Classify each equation as an identity or a contradiction.

6 x + 3 ( 1 2 x ) = 3

identity, 3 = 3

Got questions? Get instant answers now!

8 m + 4 ( 2 m 7 ) = 28

contradiction, 28 = 28

Got questions? Get instant answers now!

3 ( 2 x 4 ) 2 ( 3 x + 1 ) + 14 = 0

identity, 0 = 0

Got questions? Get instant answers now!

5 ( x + 6 ) + 8 = 3 [ 4 ( x + 2 ) ] 2 x

contradiction, 22 = 6

Got questions? Get instant answers now!

Exercises

For the following problems, solve each conditional equation. If the equation is not conditional, identify it as an identity or a contradiction.

2 y + 7 = 3

y = 5

Got questions? Get instant answers now!

5 x + 6 = 9

x = 3

Got questions? Get instant answers now!

10 y 3 = 23

y = 2

Got questions? Get instant answers now!

m 11 15 = 19

m = 44

Got questions? Get instant answers now!

7 x 4 + 6 = 8

x = 8

Got questions? Get instant answers now!

3 k 14 + 25 = 22

k = 14

Got questions? Get instant answers now!

3 ( x 6 ) + 5 = 25

Got questions? Get instant answers now!

16 ( y 1 ) + 11 = 85

y = 5

Got questions? Get instant answers now!

23 y 19 = 22 y + 1

y = 20

Got questions? Get instant answers now!

8 k + 7 = 2 k + 1

k = 1

Got questions? Get instant answers now!

2 ( x 7 ) = 2 x + 5

contradiction

Got questions? Get instant answers now!

4 ( 5 y + 3 ) + 5 ( 1 + 4 y ) = 0

Got questions? Get instant answers now!

3 x + 7 = 3 ( x + 2 )

x = 3

Got questions? Get instant answers now!

4 ( 4 y + 2 ) = 3 y + 2 [ 1 3 ( 1 2 y ) ]

Got questions? Get instant answers now!

5 ( 3 x 8 ) + 11 = 2 2 x + 3 ( x 4 )

x = 19 14

Got questions? Get instant answers now!

12 ( m 2 ) = 2 m + 3 m 2 m + 3 ( 5 3 m )

Got questions? Get instant answers now!

4 k ( 4 3 k ) = 3 k 2 k ( 3 6 k ) + 1

k = 3

Got questions? Get instant answers now!

3 [ 4 2 ( y + 2 ) ] = 2 y 4 [ 1 + 2 ( 1 + y ) ]

Got questions? Get instant answers now!

5 [ 2 m ( 3 m 1 ) ] = 4 m 3 m + 2 ( 5 2 m ) + 1

m = 2

Got questions? Get instant answers now!

For the following problems, solve the literal equations for the indicated variable. When directed, find the value of that variable for the given values of the other variables.

Solve I = E R for R . Find the value of R when I = 0.005 and E = 0.0035.

Got questions? Get instant answers now!

Solve P = R C for R . Find the value of R when P = 27 and C = 85.

R = 112

Got questions? Get instant answers now!

Solve z = x x ¯ s for x . Find the value of x when z = 1.96 , s = 2.5 , and x ¯ = 15.

Got questions? Get instant answers now!

Solve F = S x 2 S y 2 for S x 2 S x 2 represents a single quantity. Find the value of S x 2 when F = 2.21 and S y 2 = 3.24.

S x 2 = F · S y 2 ; S x 2 = 7.1604

Got questions? Get instant answers now!

Solve p = n R T V for R .

Got questions? Get instant answers now!

Solve x = 4 y + 7 for y .

y = x 7 4

Got questions? Get instant answers now!

Solve y = 10 x + 16 for x .

Got questions? Get instant answers now!

Solve 2 x + 5 y = 12 for y .

y = 2 x + 12 5

Got questions? Get instant answers now!

Solve 9 x + 3 y + 15 = 0 for y .

Got questions? Get instant answers now!

Solve m = 2 n h 5 for n .

n = 5 m + h 2

Got questions? Get instant answers now!

Solve t = Q + 6 P 8 for P .

Got questions? Get instant answers now!

Solve A star = + 9 j Δ for j .

j is equal to the product of star and triangle minus square over nine.

Got questions? Get instant answers now!

Exercises for review

( [link] ) Simplify ( x + 3 ) 2 ( x 2 ) 3 ( x 2 ) 4 ( x + 3 ) .

( x + 3 ) 3 ( x 2 ) 7

Got questions? Get instant answers now!

( [link] ) Find the product. ( x 7 ) ( x + 7 ) .

Got questions? Get instant answers now!

( [link] ) Find the product. ( 2 x 1 ) 2 .

4 x 2 4 x + 1

Got questions? Get instant answers now!

( [link] ) Solve the equation y 2 = 2.

Got questions? Get instant answers now!

( [link] ) Solve the equation 4 x 5 = 3.

x = 15 4

Got questions? Get instant answers now!

Questions & Answers

how do you get the 2/50
Abba Reply
number of sport play by 50 student construct discrete data
Aminu Reply
width of the frangebany leaves on how to write a introduction
Theresa Reply
Solve the mean of variance
Veronica Reply
Step 1: Find the mean. To find the mean, add up all the scores, then divide them by the number of scores. ... Step 2: Find each score's deviation from the mean. ... Step 3: Square each deviation from the mean. ... Step 4: Find the sum of squares. ... Step 5: Divide the sum of squares by n – 1 or N.
kenneth
what is error
Yakuba Reply
Is mistake done to something
Vutshila
Hy
anas
hy
What is the life teble
anas
hy
Jibrin
statistics is the analyzing of data
Tajudeen Reply
what is statics?
Zelalem Reply
how do you calculate mean
Gloria Reply
diveving the sum if all values
Shaynaynay
let A1,A2 and A3 events be independent,show that (A1)^c, (A2)^c and (A3)^c are independent?
Fisaye Reply
what is statistics
Akhisani Reply
data collected all over the world
Shaynaynay
construct a less than and more than table
Imad Reply
The sample of 16 students is taken. The average age in the sample was 22 years with astandard deviation of 6 years. Construct a 95% confidence interval for the age of the population.
Aschalew Reply
Bhartdarshan' is an internet-based travel agency wherein customer can see videos of the cities they plant to visit. The number of hits daily is a normally distributed random variable with a mean of 10,000 and a standard deviation of 2,400 a. what is the probability of getting more than 12,000 hits? b. what is the probability of getting fewer than 9,000 hits?
Akshay Reply
Bhartdarshan'is an internet-based travel agency wherein customer can see videos of the cities they plan to visit. The number of hits daily is a normally distributed random variable with a mean of 10,000 and a standard deviation of 2,400. a. What is the probability of getting more than 12,000 hits
Akshay
1
Bright
Sorry i want to learn more about this question
Bright
Someone help
Bright
a= 0.20233 b=0.3384
Sufiyan
a
Shaynaynay
How do I interpret level of significance?
Mohd Reply
It depends on your business problem or in Machine Learning you could use ROC- AUC cruve to decide the threshold value
Shivam
how skewness and kurtosis are used in statistics
Owen Reply
yes what is it
Taneeya
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