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evaluate the following integral:

[tex]\int x \sqrt{x^2+a^2}dx [/tex]

definite integral from 0 to a

what I did was

u = x^2 + a^2

du = 2xdx

1/2 sqrt(u)du

I just dropped the a^2 because we were finding the derivative of x but feel that it's very wrong.

Any suggestions are much appreciated.

thanks.

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# Integration by substitution

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