\sum_{n=1}^{\infty } )/n)x^n
find the interval of convergence.

(-1,1).

Step-by-step explanation:

We need to calculate where R is the radius of convergence.

Applying LHopital rule we obtaing that the limit is 1. So then R = 1.

As the serie is the form we center the interval in 0. So the interval is (0-1,0+1) = (-1,1). We don't include the extrem values -1 and 1 because in those values the serie diverges.

point a is the center of the circle that passes through points e, f, and g and the center of the circle that passes through points x, y, and z.