i'm trying to find the integral of 4/(6x+9). I let u be equal to 6x+9 and du be 6dx. Thus it is (4/6)lnu=(2/3)ln(6x+9). However my calculator says it is (2/3)ln(2x+3)...They are obviously different..What am i doing wrong?

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- March 16th 2010, 11:03 PMbfpriConfused about simple u substition problem for natural log
i'm trying to find the integral of 4/(6x+9). I let u be equal to 6x+9 and du be 6dx. Thus it is (4/6)lnu=(2/3)ln(6x+9). However my calculator says it is (2/3)ln(2x+3)...They are obviously different..What am i doing wrong?

- March 16th 2010, 11:09 PMAnonymous1
Wait a minute... Are you sure thats what your calculator says? Because mine doesn't.

http://integrals.wolfram.com/index.j...9&random=false - March 16th 2010, 11:29 PMbfpri
Yeah..thats what my TI-89 and my teacher says it is...

- March 16th 2010, 11:42 PMredsoxfan325