Question 1.
(a) Determine the Fourier series of the function
f(x) = 4 - x^2 0 < x < 2
extended to an odd function on -2 < x < 2 and then periodically to R.
(b) Plot the graphs of f and its odd extension to -2 < x < 2. Furthermore produce three plots of the Fourier series, containing the first 10, 20, and 50 terms, respectively. The plots should have domain -4 ≤ x ≤ 4 and range [-5, 5]. If you do not have a computer, handmade sketches are OK.
(c) What does this Fourier series converge to? Explain your answer by quoting an appropriate result from the slides.
(d) Use your result to compute
∑_{k=0}^{∑} (-1)^k (8 / (̀(2k + 1)) + 32 / (̀^3(2k + 1)^3)).