Dear Richard,
Thank you for this note.
But after applying solve() I have
8/25 17/25 77/100
77/100
Qs A (776 r MLSS SSVI + 776 MLSS SSVI
)
(%o3) [A = -----------------------------------------------------------]
17/25
238125 r
So all that would be needed would be to divide both sides by A^(17/25)
and then extract a root.
I can get to this by doing the following:
(%i4) %o3 / A ^ (17/25)
(%i5) %o4 ^ (25/8)
What prevented the solve() routine from recognising the last two steps?
Regards,
Jeremy
-----Original Message-----
From: Richard Fateman [mailto:fateman at cs.berkeley.edu]
Sent: Friday, June 22, 2007 8:46 PM
To: Dudley, Jeremy
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] Solving an equation
Solve doesn't do anything useful with exponents like 0.68.
Converting 0.68 to an exact rational, 17/25, it is possible to
transform your problem into a polynomial of degree 17 in a^(1/25).
Where b=a^(1/25), the equation looks like
128575 * (qs^(1/25))^17 * (r^(1/25))^17
* (((1/ssvi))^(1/100))^77 * b^25
+ ( - 419 * mlss * qs * r - 419 * mlss * qs) * b^17
or k1*b^25 +k2*b^17.
for some messy constants k1, k2. There are 9 solutions, one of them
being b=0, with multiplicity 9.
RJF
Dudley, Jeremy wrote:
>I define
>
>(%i1) X: Qs * MLSS * (1 + r) / A
>
>(%i2) X = 8.85 * (100 / SSVI)^0.77 * (Qs * r / A)^0.68
>
>(%i3) solve(%i2, A)
>
>Expecting to get A = f(Qs, MLSS, SSVI, r)
>
>Instead I get A on both RHS & LHS, and cannot find a suitable
'simplify'
>command to get the equation fully explicit in A.
>
>How do I persuade Maxima to give me a fully explicit solution?
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