Find the interval of convergence of the power series ∑(x-2)n / 3n
ρn = |an+1| / |an|
The Attempt at a Solution
I got that ρn = | (x-2) / 3 |. I set my ρn ≤ 1, since this is when the series would be convergent. Manipulating that expression, I got that the interval of convergence is -5 ≤ x ≤ 5. The answer in the back of the book is -1 ≤ x ≤ 5. I am confused where the -1 comes from.