4. Let f(x) = ln(1 + 2x). (8 points)
(a) Find the third-degree Taylor polynomial of f(x) centered at a = 1.
(b) Find an upper bound for the error if f(x) is approximated with T3(x) for
0.5 ≤ x ≤ 2.
5. Use Euler’s method with h = 0.2 to approximate y(0.4), where y is the solution
to the initial value problem y' = 2x^2y, y(0) = 1.