How to solve the following quadratic inequality:
0.3<2xx2+4<0.5
The call to solve function return the following output:
sage:
sage: solve( [(2*x / (4+x**2)) < .5 , (2*x / (x**2 + 4)) > .3 ], x, to_poly_serve=True )
[[-2*x/(x^2 + 4) + 0.5 > 0, 2*x/(x^2 + 4) - 0.3 > 0]]
sage:By hand calculation I found the following answer (2/3,2)∪(2,6).
Symbolic and numerical do not like eachother, instead of 0.5 and 0.3, use 1/2 and 3/10 :
sage: solve( [(2*x / (4+x**2)) < 1/2 , (2*x / (x**2 + 4)) > 3/10 ], x)
[[(2/3) < x, x < 6, x - 2 != 0]]but the answer doesn't contain the last part (2, 6)
Yes, it does: the first two inequalities define the interval (2/3,6), the last term removes 2 from the interval.
Thanks, I didn't notice it.
Asked: 4 years ago
Seen: 809 times
Last updated: May 09 '20
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