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 Literal Equations
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hoshimori
New Member

USA
1 Posts

Posted - 10/02/2007 :  20:36:50  Show Profile
HOW ON EARTH DO YOU SOLVE LITERAL EQUATIONS??

For example:

ab=c, solve for b

Do you first divide "a" from both sides?
I'm just really confused. Please give a thorough and basic summary of how to solve literal equations.

Edited by - hoshimori on 10/02/2007 20:38:02
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the_hill1962
Advanced Member

USA
1468 Posts

Posted - 10/03/2007 :  13:34:14  Show Profile
Solving literal equations is very confusing to beginning math students! At first, a student is taught "to solve for the variable is to find out what it is EQUAL to". It is always a numerical value. Then, all of a sudden, they are told to "solve" but the answer does not appear to be an 'answer' (e.g. x=5 or y=-34).
Here are a couple of websites that might help you out:
http://www.math.unt.edu/mathlab/emathlab/Solving%20Literal%20Equations.htm
http://www.purplemath.com/modules/solvelit.htm
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the_hill1962
Advanced Member

USA
1468 Posts

Posted - 10/03/2007 :  15:55:08  Show Profile
I liked how you put the numerical examples in your original post.
The way that I like to introduce "solving literal equations" is by going back to a basic problem such as 2x+5=19 and then I ask the question 'could you solve for x if the equation was' 2x+a=19 ?
quote:
Originally posted by David

Agreed. Everything is confusing to beginning math students! They can best learn at first, whenever possible, by seeing patterns in numerical operations, and then using exactly the same processes with literal values. In the long run, what makes the change is practice and noticing patterns [or having them pointed out.]


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Inkcoder
Junior Member

USA
3 Posts

Posted - 10/04/2007 :  21:23:44  Show Profile
If the problem was 7a=700 how would solve it..

STEP 1: 7a=700
STEP 2: 77a=7007

Divide by 7 ON BOTH SIDES
7/7=1 So really 1*a=a. Now a=700/7, a=100.

STEP 3:a=100 BINGO, You've solved the Problem.


ab=c: Nothing different about this problem. Use the same exact steps.

Edited by - Inkcoder on 10/04/2007 21:28:30
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the_hill1962
Advanced Member

USA
1468 Posts

Posted - 10/05/2007 :  07:38:44  Show Profile
Step 2 below could be a little confusing to a beginning math student (and 'technically' it is formatted wrong anyway). I have cleaned it up a little (see the second copy below this one):
quote:
Originally posted by Inkcoder

If the problem was 7a=700 how would solve it..

STEP 1: 7a=700
STEP 2: 77a=7007
The above line is not formatted correctly. See the corrected copy of this post following this copy.
Divide by 7 ON BOTH SIDES
7/7=1 So really 1*a=a. Now a=700/7, a=100.

STEP 3:a=100 BINGO, You've solved the Problem.


ab=c: Nothing different about this problem. Use the same exact steps.


Here it is formatted correctly (and after this copy, I have added another variable to it to make it into a "solve literally for t. Note that I added the t and went through it as if it was one of those solve literal types of problems:


If the problem was 7a=700 how would solve it..

STEP 1: 7a=700
STEP 2: 7a7=7007

Divide by 7 ON BOTH SIDES
7/7=1 So really 1*a=a. Now a=700/7, a=100.

STEP 3:a=100 BINGO, You've solved the Problem.


ab=c: Nothing different about this problem. Use the same exact steps.


Here is how it could have been a "solve literally for t" problem:

If the problem was 7at=700 how would you solve for t?
STEP 1: 7at=700
STEP 2: 7a7a=7007a

Now t=700/7a

Notice the confusing end to these "solve literal" problems is that you are finished even though it does not appear to be finished (no specific numerical value).
The "answer" would be just "t=700/7a" but of course, you would want to (or NEED to if your instructor requires it) simplify it to get
t=100/a since 700/7=100. The answer would be "t=100/a"

Edited by - the_hill1962 on 10/05/2007 07:54:55
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