(Original post by lollage123)
This is the part which did my head in. Does noticing this sort of thing just become a knack after time? As all I did was just blindly carry on (and wrongly cancel down)..
Thank you all for your help
If it is a knack then the knack is in reading the question - the question says show that [...] = something divided by (x+3) and you have something divided by (x+3)(x-1) therefore (unless the question wrong) the (x-1) must cancel. As this is not initially obvious but one term contains (x-1) then the other must as well. It is then merely showing this.