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I have an equation (parentheses are used because of VBA code)

Y=(P/(12E((bt^3)/12))*A

and i know every variables but not "b". Is there any way how to ask Wolfram Alpha to "redefine" (not solve) equation so I can see something like following: I tried to do it manually (but result is not OK)

b=((P/EY)*12A))/t^3

I wish to see how right equation will look.

Original equation is on picture below

enter image description here

where

enter image description here

equation in [,] I simplified by A

alexwlchan
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SilentCry
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2 Answers2

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I'm not sure if there's a way to tell Wolfram|Alpha to rearrange for a particular variable; in general it will usually try to rearrange for x or y.

If I substitute b for x in your equation and use the following query:

solve Y - (P/(12E((xt^3)/12))*A) = 0

then Wolfram Alpha returns the result you're looking for: x (b) expressed in terms of the other variables. Specifically:

x = A P / (E t^3 Y)  for  tY != 0  and AP != 0
alexwlchan
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1

I know that your question was about Wolfram Alpha, that you do not want to "solve", but here is one way you could do it in Mathematica using your real question. I renamed I into J because I is a reserved symbol in Mathematica for the imaginary unit.

J = b t^3/12;

expr = (P / (12 E J) ) (4 L1^3 + 3 R ( 2 Pi L1^2 + Pi R^2 + 8 L1 R ) + 12 L2 (L1 + R)^2)

Solve[ Y == expr , b]

Result

{{b -> (P (4 L1^3 + 12 L1^2 L2 + 24 L1 L2 R + 6 L1^2 \[Pi] R + 24 L1 R^2 + 12 L2 R^2 + 3 \[Pi] R^3))/(E t^3 Y)}}
ogerard
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