<< 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

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
Husseini Reply
Hi
mostafa
hi
LEMLEM
hello
Sammol
hi
Mahesh
bi
Ruqayat
hi
Ruqayat
Hi fellas
Nyawa
hey
Sammol
hi
God
hello
Jahara
Good morning
Jorge
hi
abubakar
hi
Nmesoma
hi
Mahesh
Hi
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
Hi
Isiaka
Hi
Geli
hy
Man
👋
Bahunda
hy how are you?
Man
ys
Amisha
how are you guys
Sekou
f9 guys
Amisha
how are you guys
Sekou
ys am also fine
Amisha
fine and you guys
Geli
from Nepal
Amisha
nawalparasi district from belatari
Amisha
nd u
Amisha
I am Camara from Guinea west Africa... happy to meet you guys here
Sekou
ma management ho
Amisha
ahile becheclor ho
Amisha
hjr ktm bta ho ani k kaam grnu hunxa tw
Amisha
belatari
Amisha
1st year ho
Amisha
nd u
Amisha
ahh
Amisha
kaha biratnagar
Amisha
ys
Amisha
kina k vo
Amisha
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
all of you please speak in English I can't understand you're language
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
Mercy is it clear?😋
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
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