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
.


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