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Topic: How to discard negative solutions
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Dr. Robert Kragler

Posts: 20
Registered: 3/18/08
How to discard negative solutions
Posted: Dec 31, 2012 7:45 PM
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Hi,
from a geometric problem I obtain with $Assumptions = {a > 0, b > 0, c > 0}
using Solve a series of solutions such as
{b -> a, c -> a} but also {c -> -a - b}.
The latter one should obviously be discarded because it will be negative
according to the assumptions (a>0, b>0) above.
How can these negative solutions being excluded by Mathematica V8 ? Positve[]
and NonNegative[] do not help because quantities which are not NumericQ remain
unevaluated. Help is appreciated.

Robert Kragler




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