Integration problem

David Ng shared this problem 9 months ago
In Progress

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)))

Comments (4)

photo
1

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

photo
1

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

photo
1

Correct answer seems to be 0.8484...

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

© 2021 International GeoGebra Institute