Integration problem

David Ng shared this problem 2 years ago

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Hi, the following double integral is returning the wrong answer. I've double checked and am very confused by the answer that geogebra returns. The correct answer should be +0.5 more.

ln(1-x+sqrt((1)/(4)+(1-x)^(2)))

The same problem

Comments (4)

Simona Riva ● 2 years ago

Please post your file, and tell us more about which version of ggb you are using (Classic, Suite...) version number and your OS.

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David Ng ● 2 years ago

Sorry, in my haste I made a mistake. The double integral is

Integral(Integral(sqrt(1+4y^2),y,1-x,1),x,0,1)

I have tried it using the online web version of CAS and I got the answer ~ 0.3484

But using the offline version 6.0.609.0 of CAS geogebra (Windows 10), the answer is ~ 0.8484

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Michael Borcherds ● 2 years ago

Correct answer seems to be 0.8484...

((5 * sqrt(5)) - (3 * ln(sqrt(5) + 2)) - (3 * ln(sqrt(5) - 2)) - 1) / 12

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Michael Borcherds ● 2 years ago

Thanks, we'll check

https://www.geogebra.org/ca...

https://www.geogebra.org/m/uggpxnqc

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