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Replies: 1   Last Post: May 1, 2013 3:35 AM

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 Chris Arthur Posts: 28 Registered: 10/4/11
Posted: Apr 26, 2013 11:08 PM

Hello,

I've discovered that Solve[] gives me the wrong answer for some
polynomial equations. For example, consider the following equation,
which should have exactly one positive, real answer for t.

p:=(px + t vx)^4 + (py + t vy)^4==1
r:={px->0.5,py->0.5,vx->0.5,vy->0.5}
NSolve[p/.r,t]

NSolve gives the right answers if I substitute for px,py,vx and vy
before solving. On the other hand, if I use Solve[] this way:

Solve[p,t]/.r

I get a different answer, and it's not correct.
Does Solve[] just malfunction with quartic polynomials or is there
something else happening?

Chris

mathematica 5.2

Solve[p]

Date Subject Author
4/26/13 Chris Arthur
5/1/13 Daniel