# How do you write an nth term rule for #1,-4,16,-64# and find #a_6#?

##### 1 Answer

#### Explanation:

The series here looks to be:

This does present a slight ambiguity in the way the question was asked. That is, if we assume that we start counting from

However if we want to start counting from

The later formula is advantageous in that the

Thus, it is not completely clear what the *correct* answer would be for

It may be:

if we started counting from

Or

if we started counting from

We'll note that the first answer is actually the 6th term in the series, while the second is actually the 5th. If this problem were presented on homework I would most likely ask for clarification from the instructor.