3.07  Literal Equations

Basic Algebra: One Step at a Time,  Page 293-296:   #9, 10, plus 2 extra problems,12, 22, 25, 27, 31, 32, 33.

Bittinger:   p.101:  17, 21, 31, 37, 53. 

Dr. Robert J. Rapalje

Seminole State College of Florida

Sanford, FL  32773

 

To see Section 3.07, with explanations, examples, exercises, and answers, click here!

 

9.   Solve for x:          .

Solution:  First, remove parentheses by the distributive property.

                                       

Next, get all the  terms on the left side by subtracting   from each side.  At the same time, subtract  to each side to get all the non- terms on the right side of the equation

                                        

Now, factor the common factor of x:

                                        

Finally, since the x has been multiplied by , you must divide both sides of the equation by .

    

                                           

NOTE:  Don't be tempted to divide out the a or the c!  These are "terms"!  Never divide out TERMS--only FACTORS!!

10.   Solve for x:          .

Solution:  First, remove parentheses by the distributive property.

                                       

Next, get all the  terms on the left side by adding   from each side.  At the same time, add  to each side to get all the non- terms on the right side of the equation

                                        

Now, factor the common factor of :

                                        

Finally, since the x has been multiplied by , you must divide both sides of the equation by .

    

                                           

NOTE:  Don't be tempted to divide out the a or the c!  These are "terms"!  Never divide out TERMS--only FACTORS!!

 

Extra Problem #1 (from Chris).     

Solve for x:          .

Solution:  First, remove parentheses by the distributive property.

                                       

Next, get all the x terms on the left side by subtracting   from each side.  At the same time, add  to each side to get all the non-x terms on the right side of the equation

                                        

Now, factor the common factor of x:

                                        

Finally, since the x has been multiplied by , you must divide both sides of the equation by .

    

                                           

Extra Problem #2

Solve for x:          .

Solution:  First, remove parentheses by the distributive property.

                                       

Next, get all the x terms on the right side by adding   from each side.  At the same time, subtract  from each side to get all the non-x terms on the left side of the equation

                                        

Now, factor the common factor of x:

                                        

                                        

Finally, since the x has been multiplied by , you must divide both sides of the equation by .

    

                                           

 

 

12.   Solve for x:          .

Solution:  First, remove parentheses by the distributive property.

                                       

Next, notice that there is only one term, which is on the right side of the equation.  Therefore, you must get the non- terms all on the left side by adding   from each side. 

                                        

Finally, in order to solve for  ,

                                           

you must divide both sides of the equation by .

        

                                           

NOTE:  Don't be tempted to divide out the!  The in the numerator is a  "term"!  Never divide out TERMS--only FACTORS!!

 

22.            ,  solve for .

Solution:  Since you are solving for , and the  has been multiplied by ,  you must “undo” the multiplication, by dividing both sides by :

                                          

                                            

                                               

 

25.            ,  solve for .

Solution:  Since there is a denominator of , multiply both sides by  to clear the fraction!

                                            

                                           

Next, remember that you are solving for , and the   has been multiplied by .  In order to “undo” the multiplication, you must divide both sides by :

                                          

                                                                                  

27.            ,  solve for .

Solution:  Since there is a denominator of , multiply both sides by  to clear the fraction!

                                       

                                           

Next, remember that you are solving for , and the   has been multiplied by and .  In order to “undo” the multiplication, you must divide both sides by and :

                                          

                                        

                                         

 

28.       Given    ,  solve for .

Solution:  Since there is a denominator of , multiply both sides by  to clear the fraction!

                                       

                                           

Next, remember that you are solving for , and the   has been multiplied by and .  In order to “undo” the multiplication, you must divide both sides by and :

                                          

                                        

                                          

31.    Given:    ,  solve for C.

Solution:  

There are at least two ways to solve for C in this problem.  Both are equally correct, but one is much easier that the other.  The easy way to solve this is to notice that the C has had two operations performed on it.  First, C is multiplied by the fraction , and then  was added.  To solve for C, you must UNDO these two operations in reverse order.  So, first undo the , by subtracting  from each side:

                           

                  

                   

Now, undo the multiplication by  by multiplying both sides of the equation by the reciprocal of which is

                  

        

              

 The other method involves multiplying both sides of the equation by the denominator which is  :

           

           

           

Subtract from each side:

           

           

To solve for   just divide both sides by :

           

            

This is a slightly different form of the answer obtained in the first method, if you factor out the 5, the answer will be the same as above:

              .

 

32.  Notice that this is the same problem as #11, but in reverse!  Begin with:          

          Given:      ,  solve for F.

Solution:  Begin by “undoing” the fraction   by multiplying both sides of the equation by  

             

             

Next, “undo” the  by adding a  to each side of the equation.

            

            

           

           

In conclusion, notice that the problem for #11 is the answer for #12, and vice-versa.     

 

33.    Given    ,    solve for S.

First, find the LCD, which is FSU (to all the Florida Gator and Miami Hurricane fans,  GO  FLORIDA STATE!)                         

 

In the first position, the F divides out, leaving SU

In the second position the S divides out, leaving UF

In the third position, the U divides out, leaving FS.

           

Now, in order to solve for S, you have to get all the S terms on one side of the equation.  You can do that by subtracting FS from each side of the equation.

                                               

Now, to solve for S, you have to factor out the S on the left side of the equation:

                                               

and divide both sides by  

                                                           

IMPORTANT NOTE:  This problem is very much like my own career, in that I started (and graduated!) at FSU and then ended up (and graduated also!) at UF—except that I did NOT change colors!!

 

Bittinger  Problems

Page 101:    #17, 21, 31, 37

17.  ,  solve for .

Solution:  Since you are solving for , you must isolate the  term.  Begin by eliminating the  by subtracting from each side:

   

        

This equation can be written  

       

Next, divide both sides by

        

You can divide out the 2 factors on the left side, but NOT on the right side, since the is a “TERM.”    NEVER DIVIDE OUT TERMS!!!

       

          Final Answer!!  (Other forms are also acceptable!!)

21.            ,  solve for .

Solution:  Since there is a denominator of , multiply both sides by  to clear the fraction!

                                            

                                           

Next, remember that you are solving for , and the   has been multiplied by .  In order to “undo” the multiplication, you must divide both sides by :

                                          

                                                     

 

31.    Given:    ,  solve for C.

Solution:  

There are at least two ways to solve for C in this problem.  Both are equally correct, but one is much easier that the other.  The easy way to solve this is to notice that the C has had two operations performed on it.  First, C is multiplied by the fraction , and then  was added.  To solve for C, you must UNDO these two operations in reverse order.  So, first undo the , by subtracting  from each side:

                           

                  

                   

Now, undo the multiplication by  by multiplying both sides of the equation by the reciprocal of which is

                  

        

              

 The other method involves multiplying both sides of the equation by the denominator which is  :

           

           

           

Subtract from each side:

           

           

To solve for   just divide both sides by :

           

            

This is a slightly different form of the answer obtained in the first method, if you factor out the 5, the answer will be the same as above:

              .

 

 37.                              ,  solve for .

Solution:  Since you are solving for , you must isolate the  term.  First, let’s eliminate the fraction from the problem by multiplying both sides of the equation by the denominator .

                              

As you can see, the denominator divides out:

                              

                              

Next, remove the parentheses by the Distributive Property:

                                  

In order to solve for , it might help to get the  term on the left side of the equation (to make the coefficient positive!).  Add  to each side:

                    

                   

Next, in order to isolate the , subtract  from each side:

        

                               

Finally, divide both sides by :

                              

The  on the left side divides out, but NOT on the right side.  Remember, on the right side the  is a TERM, and you NEVER divide out terms!!!

                             

The final answer is    

By the way, several other forms of the answer are equally acceptable.  For example, the three terms in the numerator can be arranged in ANY order!

 

53.  Solve for c:          .

Solution:  First, get all the terms on the left side by subtracting  from each side.

                                              

                                               

Next, you have to get the  in one place, so use the distributive property (factor out the common factor of !) to write

                                               

Finally, since the  has been multiplied by , you must divide both sides of the equation by .

    

                                           

 

 

 

Return to main page        Math in Living C O L O R !!

     Return to Basic Algebra page     Return to Intermediate Algebra page  

 Return to College Algebra page

 

Dr. Robert J. Rapalje Altamonte Springs Campus
Contact me at:   rapaljer@seminolestate.edu
Phone number:  NONE Retired!!
OFFICE:          NONE  
Copyright © Seminole State College of Florida, 1997