lool yes past papers is right..
firt you have to find the factors of the constant, in this case 30:
1,30,15,2,5,6,and the negatives of each..
and we know that (a+y) is a factor when f(-y) =0..therefore, a=1 obviously gives us zero,
and so (a-1) is a factor...
do long division, get the quadratic function, and find the solutions..
sorry 4 the late reply, i had to go lol