AP® Calculus BC · Free response

A Taylor polynomial from a table, with two error bounds

write it first, then score yourself point by point

Series and Taylor polynomials · Part B: no calculator · 9 points

The question

Name: ______________________   Date: ____________   A Taylor polynomial from a table, with two error bounds (9 points)

Table

Values of hh and its derivatives

The function hh has derivatives of all orders for x>−1x > -1. The table gives values of hh and its first three derivatives at x=0x = 0 and x=1x = 1. The fourth derivative of hh is h(4)(x)h^{(4)}(x)=960(x+1)6= \frac{960}{(x + 1)^6}. The Taylor series for hh about x=1x = 1 is ∑n=0∞(−1)n(n+1)(x−1)n2n−1\sum_{n=0}^{\infty} \frac{(-1)^n (n + 1)(x - 1)^n}{2^{n-1}}, and it converges to h(x)h(x) for −1<x<3-1 < x < 3.
Values of hh, h′h', h″h'' and h‴h'''
xxh(x)h(x)h′(x)h'(x)h″(x)h''(x)h‴(x)h'''(x)
0088−16-164848−192-192
1122−2-233−6-6
  1. (a) Write the third-degree Taylor polynomial P3(x)P_3(x) for hh about x=1x = 1. [2 points]

  2. (b) Use P3(x)P_3(x) to estimate h(1.2)h(1.2). [1 point]

  3. (c) Use the Lagrange error bound to show that |h(1.2)−P3(1.2)|<1500\left|h(1.2) - P_3(1.2)\right| < \frac{1}{500}. [3 points]

  4. (d) Explain why the alternating series error bound can be used for the estimate in part (b), and use it to find a bound on |h(1.2)−P3(1.2)|\left|h(1.2) - P_3(1.2)\right|. Can the alternating series error bound be used in the same way to bound |h(0.8)−P3(0.8)|\left|h(0.8) - P_3(0.8)\right|? Explain. [3 points]