<p>I was given the problem: Integral of ln(2x+1)dx.</p>
<p>My answer was: 1/2(2x+1)ln(2x+1)-x+1+C</p>
<p>But the answer in the book was: 1/2(2x+1)(ln2x+1)-x+C</p>
<p>Can anyone explain why I am getting that extra +1 in there? Help is appreciated.</p>
<p>I don't know what you did to get it, but your answer is still right, since 1 + a constant is still a constant.</p>
<p>I was wondering that. I guess my book just simplified further. To solve it I first substituted 2x+1 for z and 2 for dz. I then had int(lnz)dz which I solved by using parts.</p>