Simplify,

I get the principle i.e. multiply denominators to find common denominator, add, factor, simplify. I've done loads of examples but for some reason I just can't get this one. I know it's relatively straight forward, I think my problems somewhere in the simplification/indices area.

I get as far as:-

At this point it all seems to get overly complicated.

Anybody break it down a bit for me?