In Problems 1-4, find the convergence set for the given power series. Find a formula for the

Question:

In Problems 1-4, find the convergence set for the given power series. Find a formula for the nth term; then use the Absolute Ratio Test?
1. x / 1 ( 2 - x2 / 2 ( 3 + x3 / 3 ( 4 - x4 / 4 ( 5 + x5 / 5 ( 6 - ...
2. 1 + x + x2 / 2! + x3 / 3! + x4 / 4! + ...
3. x - x3 / 3! + x5 / 5! - x7 / 7! + x9 / 9! - ...
4. 1 - x2 / 2! + x4 / 4! - x6 / 6! + x8 / 8! - x10 / 10! + ...