Two terms before it. Since n=4, the 1/5 cancels with the 1/5 from n=2
From a quick glance, looks like you're right. (Can't do the question myself right now) does the markscheme say it's included? Have you looked at the direction of the cancelling? Probably best just to put your working up tbh.
From a quick glance, looks like you're right. (Can't do the question myself right now) does the markscheme say it's included? Have you looked at the direction of the cancelling? Probably best just to put your working up tbh.