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exponential inequality

asked 2017-05-25 02:56:44 -0600

soking gravatar image

updated 2017-05-25 03:37:54 -0600

Hi all, I am trying to solve, using sage, the inequality exp(x) >= 5, but this is what I get

sage: solve(exp(x)>=5,x)
#0: solve_rat_ineq(ineq=%e^_SAGE_VAR_x >= 5)
[[e^x - 5 == 0], [e^x - 5 > 0]]

Can anyone tell me what's wrong and how to solve this kind of inequalities?

Thanks

sorry for the presentation of the code, I am new on this plateform.

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Comments

Instead of starting the lines of coes with >, you just have to start each line with 4 spaces. This can be done automatically by selecting your code bloc with the mouse/trackpad and then click on the 101010 icon.

tmonteil gravatar imagetmonteil ( 2017-05-25 03:22:02 -0600 )edit

ok, thanks for the comment, but I still don't have an answer to my question^^

soking gravatar imagesoking ( 2017-05-25 03:39:00 -0600 )edit

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answered 2017-05-25 03:50:40 -0600

tmonteil gravatar image

You can use sympy:

sage: import sympy
sage: x = sympy.Symbol('x')
sage: ineq = sympy.exp(x) >= 5
sage: ineq
exp(x) >= 5
sage: type(ineq)
<class 'sympy.core.relational.StrictGreaterThan'>
sage: sympy.solve_univariate_inequality(ineq,x)
And(log(5) <= x, x < oo)
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Great, it works. Thanks a lot.

soking gravatar imagesoking ( 2017-05-25 05:40:59 -0600 )edit

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Asked: 2017-05-25 02:56:44 -0600

Seen: 52 times

Last updated: May 25