ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 06 Oct 2013 06:39:15 +0200Wrong solution?https://ask.sagemath.org/question/10592/wrong-solution/Hi, could you help me with this solution of two equations on the interval:
x,a=var('x,a')
f1=10/x
f2=x-**5***a
**assume(a>0,x>0)**
print(solve([f1==f2],x))
Solution given by Sage is:
[
x == 5/2*a - 1/2*sqrt(25*a^2 + 40),
x == 5/2*a + 1/2*sqrt(25*a^2 + 40)
]
The first solution is obviously not solution for me as it is always strictly negative and I don't understand why the Sage gave me it. Assumptions are clear: **x** has to be **>0** When I change second equation slightly:
x,a=var('x,a')
f1=10/x
f2=x-**6***a
**assume(a>0,x>0)**
print(solve([f1==f2],x))
Solution given by Sage is correct now (only the x>0 are reported):
[
x == 3*a + sqrt(9*a^2 + 10)
]
Could you help me explain the difference in results. I am not sure if problem is on python side or with some rules how Sage computes the results.
Thank you in advance.
J.T.Sun, 06 Oct 2013 06:39:15 +0200https://ask.sagemath.org/question/10592/Please help me to draw f(x) = sin(x) if x<=0 and f(x)=cos(x) if x>1https://ask.sagemath.org/question/10226/please-help-me-to-draw-fx-sinx-if-x0-and-fxcosx-if-x1/thanks for your answers
noufalasharafWed, 12 Jun 2013 14:33:24 +0200https://ask.sagemath.org/question/10226/