The problem I'm having is the solution I get on sage when solving the following inequality
[(4*x+5)/(x^2)>=4/(x+5)]
It gives me the wrong answer
([x < -5], [x >= -1])
the answer should be
(x<-5),(-1<=x<0),(0<x<oo).
The answer can be checked at here at wolframalpha. I'm still new to sage and in the learning process I don't know if I might be doing something wrong.
The problem seems to be that Sage makes sense of "+infinity > finite number" situations. Even in the following where both sides of the inequality are infinite
sage: A = (4*x+5)/(x^2)
sage: B = 4/(x+5)
sage: solve(A >= B, x)
[[x < -5], [x >= -1]]
sage: solve(A/x^2 >= B/x^2, x)
[[x < -5], [x >= -1]]
Vincent
Asked: 2015-10-17 18:15:53 +0100
Seen: 272 times
Last updated: Oct 17 '15
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