Can someone please explain it to me ASAP???!!! This is Alternating Series and Absolute Convergence.

Let E (- 1)* *ax be a convergent alternating series with terms that are nonincreasing in magnitude, Let Ry = S - S,, be the remainder in approximationg the value of K = 1 that series by the sum of its first n terms. Then |R | san + 1 . In other words, the magnitude of the remainder is less than or equal to the magnitude of the first neglected term. For the convergent alternating series ) (-1) (4k + 1)3 . evaluate the nth partial sum for n = 2. Then find an upper bound for the error S - S, | in using the nth partial sum S,, to estimate the value of the series S. The nth partial sum for the given value of n is (Type an integer or a decimal, Round to seven decimal places as needed.)