# Math Help - infinite sum problem

1. ## infinite sum problem

i need help to find the sum of 1 to infinity of 4 (-3)to the power of x

2. Originally Posted by helpless13
i need help to find the sum of 1 to infinity of 4 (-3)to the power of x
No, this is not clear. It seems to be asking for:

$\sum_{r=1}^{\infty} 4 \times (-3)^r$

which is not convergent.

RonL

3. ## not clear

it isn't clear but I have a formula that says if k<1 , k being the common ratio than the sum is

A1
1-K which is -3 and I don't know if that is right

4. Originally Posted by helpless13
it isn't clear but I have a formula that says if k<1 , k being the common ratio than the sum is

A1
1-K which is -3 and I don't know if that is right
It's |k| (absolute value) that has to be <1.
Here, |-3|=3 > 1.