algebra manipulation problem

hi,



I know this is pretty basic stuff but could someone please talk me through this? I can see that one bracket is made up of the common factor and the other is made of the two number which were outside the bracket, but how does this work?

Thanks

To make it easier to see, set

So we have:


See how the u factors out? It probably just looked more complicated but if you boil it down, it isn't so bad ;)

ah, thanks, it really is much clearer when you call u = 3x+2.

Thanks again.