Math Challenge N 1 - Calculate integral

Welcome everybody this article is just for students and for the people who are interested about math, So I will publish different posts just like that ( exercises with solutions ) to improve ours skills and be good at math and of course you can participate and give us you methods and discuss about different ideas .

Our exercise here is about calculate a simple integrale in differents way so I will post my method and if you have another method please rich us with your knowledge.

Here is the solution :

Please dont use programs like mapple mathematica axiom ...
And remember that I am not a teacher or something like that so I can be wrong but I hope I'm not.

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