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# Algebra/Simple Algebra

Question
Hi Scott

My non-math mind wants to know the following:

I am reading a textbook where the equation

MOE = PL^3 / 48ID

is presented.  Then they solve for D

D = PL^3 / 48(MOE)I.

It looks like they simply had D and MOE change places.  But I'm not satisfied.  I would like to know the algebra rule whereby the equation can be solved for D.

Thanks!

Pete

Technically, the equation should really be written with parenthesis to be sure the terms are all in the denominator on the right side.  Then it would be MOE = PL^3 / (48ID).

If both sides are multiplied by D, that gives MOED on the left side and
on the right side we have DPL^3 / (48ID), and D/D is 1, giving PL^3 / (48I).

Now that we have MOED = PL^3 / (48I), multiply both sides by 1/(MOE).
On the left side, we get MOED / (MOE) = D.
On the right side, we have [PL^3 / (48I)][1/(MOE)].
That multiplies out to PL^3 / (48IMOE).

This makes the final equation be D = PL^3 / (48IMOE).
Questioner's Rating
 Rating(1-10) Knowledgeability = 10 Clarity of Response = 10 Politeness = 10 Comment Hey that's a pretty neat trick, Scotto; I'll have to remember that one. Who knows when I'll encounter a similar situation. P

Algebra

Volunteer

#### Scott A Wilson

##### Expertise

Any algebraic question you've got. That includes question that are linear, quadratic, exponential, etc.

##### Experience

I have solved story problems, linear equations, parabolic equations. I have also solved some 3rd order equations and equations with multiple variables.

Publications
Documents at Boeing in assistance on the manufacturiing floor.

Education/Credentials
MS at math OSU in mathematics at OSU, 1986. BS at OSU in mathematical sciences (math, statistics, computer science), 1984.

Awards and Honors
Both my BS and MS degrees were given with honors.

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Students in a wide variety of areas since the 80's; over 1,000 of them have been in algebra.