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If I have the indefinite integral x(sqrt(4-x^2))dx

must I replace x with 2sint and then dx = 2cosdt

or can I just do regular substitution with u = 4-x^2 since xdx occurs in the integral already.

when I solve it this way I get -1/3(4-x^2)^3/2 + C

it just seems alot more work to do it the trigonometric substitituon way.

Any help is much appreciated. Thanks!!

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# Trig substition confusion

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