isolate variable

[Davidro]

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

[victorvbc]

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

[Davidro]

(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

[victorvbc]

Also, you can of course solve numerically (fsolve) for values of y, or graphically using the implicit plot in the advanced graphing app.

   

[CyberAngel]

(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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