How solve

08082017, 03:48 AM
Post: #1




How solve
1x*2.72^(50*y)=100/z
1x*2.72^(100*y)=150/z 1x*2.72^(150*y)=250/z 

08082017, 03:05 PM
Post: #2




RE: How solve
With a pen and paper? \(x=\frac12\), \(y=\frac{\log_{2.72}2}{50}\), \(z=50\)


08082017, 03:10 PM
Post: #3




RE: How solve
Starting values? Any ideas what the feasible solution space should look like?
Using fsolve(), with blind values x=.1, y=.1,z=.1*i, I get [.5, 1.38 . . .E2, 50]. 

08092017, 01:52 AM
Post: #4




RE: How solve  
08092017, 03:26 AM
Post: #5




RE: How solve
solve([1x*e^(?50*y)=100/z,1x*e^(?100*y)=200/z,1x*e^(?150*y)=250/z],[x,y,z])
[/b] ["[y,e^(50*y),e^(100*y),e^(150*y)] is not rational w.r.t. y Erreur: Valeur Argument Incorrecte"] fsolve([(1x*e^(50*y)) = (100/z),(1x*e^(100*y)) = (200/z),(1x*e^(150*y)) = (250/z)],[x,y,z],[0.1,0.1,0.1*i]) undef Above output is the result from HP Prime Graphing Calculator, something wrong with it, please help me check if there is any input mistake. 

08092017, 05:52 AM
Post: #6




RE: How solve
You can help solve by rewriting the system as a rational system
Code: solve([(1x*t) = (100/z),(1x*t^2) = (150/z),(1x*t^3) = (250/z)],[x,t,z]) Code: solve(e^(50*y)=t,y) Code: fsolve([(1x*e^(50*y)) = (100/z),(1x*e^(100*y)) = (150/z),(1x*e^(150*y)) = (250/z)],[x,y,z],[0.1,0.1,0.1]) 

08092017, 09:14 AM
Post: #7




RE: How solve
i tried to input i in solve symbolic view，it shows that irror：invalid input，please help me fix this problem.


08092017, 01:58 PM
(This post was last modified: 08092017 01:59 PM by Helge Gabert.)
Post: #8




RE: How solve
You didn't use the starting values I mentioned in my above post.
[.1,.1,.1*i] Works for me. 

08092017, 03:03 PM
Post: #9




RE: How solve
What are the theory for using this starting value.
i tried to input i in solve symbolic view，it shows that irror：invalid input，please help me fix this problem. 

08092017, 04:00 PM
Post: #10




RE: How solve
I, as well as the others, I think, have not tried it in the solverapp. Switch to the commandline, I tried it in CAS, and the above mentioned entry beginning with fsolve(...) will do the job.
Arno 

08092017, 09:34 PM
Post: #11




RE: How solve
Thank you all. The members here are very active in solving the problem.


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