Math help! Senior in high school, first day of class?

Question

Today was my first day of AP Statistics and we got a worksheet covering topics we've learned since freshman year. The first question on the worksheet has me completely stumped. Its been a long summer and my brains not quite ready for all this!

In the series +1-1+1-1+1-1+... in which +1's and -1's alternate, find a formula for the nth term.

seems pretty simple right? Thanks in advance, but please explain how to get to the answer not just the answer... I want to understand how to do the problem.

Answer 1

its a summation of (-1)^(n - 1).  This is if n starts at 1.  Notice n is even, the exponent becomes odd.  When n is odd, exponent becomes even.