Inferring A General Term From A Sequence

[Bashyboy]

Homework Statement

3, -3/2, 3/4, -3/8,...

Homework Equations

The Attempt at a Solution

I began to write, $(-1)^{n+1} \frac{3}{...}$, but I began to despair once I came upon the denominator. I know that every term's, except 3, denominator can be written as a power of two, but I wasn't sure on how to account for the 3.

 

[LCKurtz]

Homework Statement

3, -3/2, 3/4, -3/8,...

Homework Equations

The Attempt at a Solution

I began to write, $(-1)^{n+1} \frac{3}{...}$, but I began to despair once I came upon the denominator. I know that every term's, except 3, denominator can be written as a power of two, but I wasn't sure on how to account for the 3.

I don't see your problem. You have the alternating sign, the 3, and powers of two. Put them all in your answer.

 

[Bashyboy]

So, would it be $(-1)^{n+1} \frac{3}{2^{n-1}}$

 

[LCKurtz]

So, would it be $(-1)^{n+1} \frac{3}{2^{n-1}}$

All you have to do is see if it gives your answers for n = 1,2,3,4.