Quote (CrackerJacker @ Aug 17 2014 11:14pm)
consider we want to integrate -1/(y-10)
what I would personally do is pull the (-1) out of the integral sign and integrate 1/(y-10), giving me an answer of -ln(y-10)
the book i'm using//wolfram alpha instead multiplies top and bottom by (-1), changing it to 1/(10-y) and yielding an answer of -ln(10-y)
Why is this? I don't think we can say -ln(10-y) = -ln(y-10)
but at the same time, whichever you choose to derive will get you an answer of 1/(10-y)
what is going on here
When you multiply by -1/-1, that makes the variable negative. so, you have to remember to divide by 1 through u substitution procedures.