So the zeros come in positive and negative pairs. If there are an odd number of intercepts like there are here, it's because one of them is x=0 which is its own negation.
Given zero x=6 we know x=-6 is also a zero.
So we know three zeros, and know the other two zeros are a positive and negative pair.
This only happens when the ordinary ratio is greater than one, the terms of the sequence will get bigger and bigger, and if you add larger numbers you won't get a definitive answer.
