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# Get rid of a variable using Simplify/Assuming

Posted 11 years ago
 Hey Community,After searching the help and web, i hope you can help me:I have the following code:eqn416 = a == Kp h (1 - E^(-ta/\[Tau]))eqn417 = a/2 == Kp h (1 - E^(-ta2/\[Tau]))Eliminate[{eqn416, eqn417}, {Kp, h}]eqn418 = Simplify[%[[2]], a != 0]But eqn418 still contains 'a'. How can I get rid of it?Or how can i get rid of it just using Eliminate?Or is there an other way do 'divide' eqn416 by eqn417?The only way to 'divide' two equations I found was doing it by Eliminate.Interesting fact: if I use the same code with 'e' instead of 'E', it will work.
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Posted 11 years ago
 Perhapsasub = First @ Solve[eqn416, a]Simplify[{eqn417} /. asub, h Kp != 0]orEliminate[{eqn416, eqn417}, {a}]eqn418 = Simplify[%[[2]], Kp h != 0]yields the desired output.
Posted 11 years ago
 Thanks for this advise. I tryed it before: With FullSimplify, I'll get a solution which gives me the same tau as "my solution",but plotting these two, will result in two completely different graphs!Since I work with a book, I would like to get the solution, the author used in his book ....
Posted 11 years ago
 Try FullSimplify.