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it seems that wxMaxima normally can't solve this simple irrational equation: 10=x-2*sqrt(x)

Here's my input and output:

(%i1)   f1(x):= x-2*sqrt(x)$
(%i1)   solve(f1(x)=10, x);
(%o1)   x=2sqrt(x)+10

I've also tried other ways of solving this but with no luck. And I can't plot this function in Maxima as well.

It's possible to solve and plot it in Wolfram Alpha so maybe there is a way to do it in wxMaxima. Do you know such workaround?

In some very old mailing list archive I came across a hint to use:

part(fundef(f1),2)

and substitute the result back to the original expression but I'm not sure how to do it. Someone also shared a code that can be used to solve irrational equations in Maxima but ufortunately this code is not attached to his reply anymore.

FEA-eng
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    For equations involving radicals, take a look at `to_poly_solve`. `?? to_poly_solve` will bring up some documentation. – Robert Dodier Apr 05 '21 at 17:11
  • Thanks, I think that I used to_poly_solve for this example before but I must have made some mistake (or missed the correct answer) because when I try it now it works perfectly and provides the right answer. Thank you again for reminding me about this solver (it's really usefull by the way). Can I plot this function in Maxima too? – FEA-eng Apr 06 '21 at 21:45
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    Yes, you can say: `plot2d (f1, [x, 0, 20]);` for example. There are many variations which also work. See also the package `draw` which can display other graphics in addition to plotting functions. – Robert Dodier Apr 06 '21 at 22:32

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