# How do you write the rule for the nth term given #-5,10,-15,20,...#?

##### 1 Answer

#### Answer:

#### Explanation:

Let the term count be

Let the i'th term be

Let the term the question askes for be

Tip: Alternating positive an negative is achieved using something like:

So this is an arithmetic sequence of type

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So for any

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For any

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~