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Student Support Forum: 'Replacing a variable with the root of an equati...' topicStudent Support Forum > General > "Replacing a variable with the root of an equati..."

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Fernando
11/17/09 11:40pm

I have a function w with a coefficient A, I do some integrals with this function and then evaluate the derivative of the function respect to A equal to zero to solve for A. I want to assign this value to A, so this is what I am doing:

w = A Sin[ Pi x/L]
I = Integral[w^2,0,L]

This integrates and gives me a function of A^2, then I do:

sol=Solve[D[I,A]==0,A]

Gives me a solution, with no problem, so I assign this value to A with

A/.sol[[1]]

Also no errors, but if I type w again, A has not been replaced.

What am I missing?


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Subject (listing for 'Replacing a variable with the root of an equati...')
Author Date Posted
Replacing a variable with the root of an equati... Fernando 11/17/09 11:40pm
Re: Replacing a variable with the root of an eq... yehuda ben-s... 11/25/09 01:48am
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