a. Use any analytical method to find the first four nonzero terms of the Taylor series centered at 0 for the following function. You do not need to use the definition of the Taylor series coefficients. b. If possible, determine the radius of convergence of the series. f(x) = cos (4x) + 3sin xDetermine the radius and interval of convergence of the following power series. 5 X7 9 X11 X ++ X 4 9 16