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+--- Thread: isolate variable (/thread-15003.html)
isolate variable - Davidro - 05-16-2020 02:36 PM
Personal:
How to isolate x in equation 1/√x=2*log((y*√x)-0,8), on HP Prime?
I looked in the groups and found no answers.
Grateful
Davidro
RE: isolate variable - victorvbc - 05-16-2020 03:01 PM
The solution for x in this particular equation can't be expressed in terms of elementary functions. It needs the product logarithm (omega function), which the calc doesn't seem to have, so it won't be able to isolate x, unfortunately.
It can isolate y though:
Code:
solve(1/sqrt(x)=2*ln(sqrt(x)*y-0.8),y)
(e^(1/(2.*√x))+0.8)/√xRE: isolate variable - Davidro - 05-16-2020 03:16 PM
(05-16-2020 03:01 PM)victorvbc Wrote: The solution for x in this particular equation can't be expressed in terms of elementary functions. It needs the product logarithm (omega function), which the calc doesn't seem to have, so it won't be able to isolate x, unfortunately.
It can isolate y though:
Code:
solve(1/sqrt(x)=2*ln(sqrt(x)*y-0.8),y)
(e^(1/(2.*√x))+0.8)/√x
Ok.,
Grateful
RE: isolate variable - victorvbc - 05-16-2020 03:19 PM
Also, you can of course solve numerically (fsolve) for values of y, or graphically using the implicit plot in the advanced graphing app.
[attachment=8474]
RE: isolate variable - CyberAngel - 05-23-2020 05:05 PM
(05-16-2020 03:01 PM)victorvbc Wrote: The solution for x in this particular equation can't be expressed in terms of elementary functions. It needs the product logarithm (omega function), which the calc doesn't seem to have, so it won't be able to isolate x, unfortunately.
X
Lambert W (as an analytic function)
has been missing ever since HP-28C.
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