Math Problem Statement

Suppose we want to approximate the value of 63^(1/3) using a Taylor polynomial. (a) Determine an appropriate power function f(x). (b) What would be an appropriate basepoint a? (c) Find T1(x). (d) Use T1(x) to estimate the value of 63^(1/3).

Solution

Let's address each part of the problem using a Taylor polynomial approximation for 631/363^{1/3}.

(a) Determine an appropriate power function f(x)f(x).

Since we want to approximate 631/363^{1/3}, a suitable choice for f(x)f(x) would be: f(x)=x1/3f(x) = x^{1/3}

(b) What would be an appropriate basepoint aa?

The basepoint aa should be a value close to 63 that makes the calculations simpler and for which we can easily find the cube root. A good choice here is a=64a = 64, since 641/3=464^{1/3} = 4.

(c) Find T1(x)T_1(x).

The Taylor polynomial of degree 1 (linear approximation) centered at a=64a = 64 for the function f(x)=x1/3f(x) = x^{1/3} is given by: T1(x)=f(a)+f(a)(xa)T_1(x) = f(a) + f'(a)(x - a)

  1. Calculate f(a)f(a): f(64)=641/3=4f(64) = 64^{1/3} = 4

  2. Calculate f(x)f'(x): The derivative of f(x)=x1/3f(x) = x^{1/3} is: f(x)=13x2/3=13x2/3f'(x) = \frac{1}{3} x^{-2/3} = \frac{1}{3 \cdot x^{2/3}}

  3. Evaluate f(64)f'(64): f(64)=13642/3=1316=148f'(64) = \frac{1}{3 \cdot 64^{2/3}} = \frac{1}{3 \cdot 16} = \frac{1}{48}

  4. Write T1(x)T_1(x): T1(x)=4+148(x64)T_1(x) = 4 + \frac{1}{48}(x - 64)

(d) Use T1(x)T_1(x) to estimate the value of 631/363^{1/3}.

Substitute x=63x = 63 into T1(x)T_1(x): T1(63)=4+148(6364)=4148=40.020833.9792T_1(63) = 4 + \frac{1}{48}(63 - 64) = 4 - \frac{1}{48} = 4 - 0.02083 \approx 3.9792

So, the estimate for 631/363^{1/3} using the Taylor polynomial T1(x)T_1(x) is approximately 3.97923.9792.

Would you like more details on any of the steps or have any questions?

Related Questions:

  1. How would the approximation improve if we used a second-degree Taylor polynomial T2(x)T_2(x)?
  2. What is the actual value of 631/363^{1/3}, and how close is the Taylor polynomial approximation?
  3. How do higher-order derivatives affect the accuracy of a Taylor polynomial?
  4. Can you use a different basepoint aa for the Taylor expansion, like a=60a = 60, and how would that change the result?
  5. What other methods can be used to approximate 631/363^{1/3} besides Taylor series?

Tip:

For better approximations, using a basepoint aa that is very close to the desired value xx often results in a more accurate Taylor polynomial approximation, especially when using only a few terms.

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Math Problem Analysis

Mathematical Concepts

Taylor Polynomials
Approximation
Derivative
Power Functions

Formulas

f(x) = x^(1/3)
T_1(x) = f(a) + f'(a)(x - a)
f'(x) = (1/3) * x^(-2/3)

Theorems

Taylor Series Expansion

Suitable Grade Level

Grades 11-12, College Level