1) The document discusses power series and calculating the radius of convergence and interval of convergence for power series. 2) There are three possible ways for a power series to converge: at a single point, for all values, or within an interval of values. The radius of convergence is half the length of the interval of convergence. 3) The ratio test is recommended for finding the radius and interval of convergence. Examples are provided of applying the ratio test to determine the radius and interval of convergence for different power series.