Re: geometric series problem

This problem is solved in a standard way, so you need to show some effort.

$\displaystyle \sum_{r=0}^\infty a^r$ converges iff $\displaystyle |a|<1$. When you are looking for the set of x for which the series converges, remember that an equality changes sign when multiplied by a negative number.

Re: geometric series problem

Re: geometric series problem

Quote:

Originally Posted by

**mastermin346** what should i do sir?

Show some effort.

What is the formula for $\displaystyle S_5 = \sum\limits_{k = 0}^5 {r^k }~? $

Re: geometric series problem

For part (a), study the definition of geometric progression and geometric series.

For part (b), I gave you a hint. I used the term "converges." By definition, a series converges iff its sum to infinity exists.