An important concept that comes from sequences is that of series
and summation. Series and summation describes the addition of
terms of a sequence. There are different types of series,
including arithmetic and geometric series. Series and summation
follows its own set of notation that is important to memorize in
order to understand homework problems. So a series is just the
summation of a sequence. So a sequence is just a bunch of
numbers in a row, a series is what happens when we add up all
those numbers together. Okay? So before me I have a general term
for a sequence. a sub n is equal to n squared minus 1. And first
we're asked to find the first four terms. Okay? So in order to
find the first term, we would find a sub 1 which happens when we
plug in 1. 1 squared minus 1 that's just 0. So our first term is
going to be 0. To find the second term we plug in 2. a sub 2 is
equal to 2 squared. 4-1 which is going to give us 3. Third term
[IB] and repeat a sub 3 is 3 squared, 9-1 is 8. And the fourth
term a sub 4,