I finished this problem only to find that the signs have changed and I am not sure why. Can someone please let me in on the secret?

Follow Math Help Forum on Facebook and Google+

No secret. The negative sign was factored out of the term and placed in front of the entire fraction in the last line.

ahhaa I actually didn't notice that negative sign at the beginning. I get it now... (a)(b)(-c) is the same at -(a)(b)(c) Thanks!