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-   -   Is it possible that Wolfram Mathematica is solving integrals wrongly? (http://mymathforum.com/calculus/342736-possible-wolfram-mathematica-solving-integrals-wrongly.html)

 srecko November 10th, 2017 01:13 PM

Is it possible that Wolfram Mathematica is solving integrals wrongly?

I think this integral calculation in Mathematica is wrong.
I am quite sure, that Mathematica works ok, while I do not understand something. Please help me.

Graphs (the red one is under the blue and the green):
http://image.ibb.co/dyD4xb/graphs.jpg
Wolfram Mathematica
http://image.ibb.co/jCWPxb/Mathematica.jpg
Symbolab:
http://image.ibb.co/mTthiG/symbolab.jpg

 Joppy November 12th, 2017 01:11 PM

Why do you think it's wrong? It's a decaying exponential.

 Country Boy November 13th, 2017 02:31 PM

How many decimal places are you allowing for the answer?

$\int_{10.3}^\infty e^{-39.1(x- 10.3}dx$
$-\frac{1}{39.1}\left[e^{-39.1(x- 10.3)}\right]_{10.3}^\infty$

$-\frac{1}{39.1}\left(0- 1\right)= \frac{1}{39.1}= 0.02557$

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