# How do you use summation notation to expression the sum #15-3+3/5-...-3/625#?

##### 1 Answer

Mar 7, 2017

Please see the explanation.

#### Explanation:

Let try to fill in the finite sum:

If your remove a common factor of 15, you get:

You can write 1 as

Because the minus sign appears on the odd powers, one can see that we are raising -5 to a negative power:

To obtain the original sum, multiply by 15: