hello from mrbilldoesmath!
answer:
a(n) - a(n-1) -3
discussion:
this ones a bit interesting. given a(n) = 5 - 3n consider this:
a(n-1) = 5 - 3(n-1)
= (5 - 3n) + 3 => but a(n) = 5 - 3n, the first term
= a(n) + 3 => subtract 3 from both sides
a(n-1) -3 = a(n)
or
a(n) - a(n-1) -3
you,
mrb