Math Problem Statement

Find the Taylor polynomial of order 2 for the function f(x) = √(1 + x/2) about the origin and use it to approximate √103. Estimate the error of the approximation by computing the remainder and finding an upper bound.

Solution

To solve these problems, we'll follow these steps:

(a) Find the Taylor polynomial of f(x)=1+x2f(x) = \sqrt{1 + \frac{x}{2}} of order 2 about the origin.

First, we find the derivatives needed:

  1. f(x)=(1+x2)1/2f(x) = (1 + \frac{x}{2})^{1/2}

    The Taylor series expansion about 0 is given by:

    f(x)=f(0)+f(0)x+f(0)2!x2+f(x) = f(0) + f'(0)x + \frac{f''(0)}{2!}x^2 + \cdots

  2. Evaluate f(0)f(0):

    f(0)=1+02=1f(0) = \sqrt{1 + \frac{0}{2}} = 1

  3. First derivative f(x)f'(x):

    Using the chain rule,

    f(x)=12(1+x2)1/212=121+x212=14(1+x2)1/2f'(x) = \frac{1}{2}(1 + \frac{x}{2})^{-1/2} \cdot \frac{1}{2} = \frac{1}{2 \sqrt{1 + \frac{x}{2}}} \cdot \frac{1}{2} = \frac{1}{4} (1 + \frac{x}{2})^{-1/2}

  4. Evaluate f(0)f'(0):

    f(0)=14f'(0) = \frac{1}{4}

  5. Second derivative f(x)f''(x):

    Differentiating f(x)f'(x),

    f(x)=18(1+x2)3/212=116(1+x2)3/2f''(x) = -\frac{1}{8} (1 + \frac{x}{2})^{-3/2} \cdot \frac{1}{2} = -\frac{1}{16} (1 + \frac{x}{2})^{-3/2}

  6. Evaluate f(0)f''(0):

    f(0)=116f''(0) = -\frac{1}{16}

  7. Taylor polynomial of order 2:

    T2(x)=1+14x132x2T_2(x) = 1 + \frac{1}{4}x - \frac{1}{32}x^2

(b) Use the result of (a) to find an approximation for 103\sqrt{103}. Estimate the error of your result by computing the remainder and finding an upper bound for it.

Express 103\sqrt{103} in terms of f(x)f(x):

  • Let x=204x = 204, then 1+2042=103\sqrt{1 + \frac{204}{2}} = \sqrt{103}.

Using the polynomial:

f(x)1+14(204)132(204)2f(x) \approx 1 + \frac{1}{4}(204) - \frac{1}{32}(204)^2

Calculate the approximation:

f(x)1+2044204232f(x) \approx 1 + \frac{204}{4} - \frac{204^2}{32}

Estimate the error using the remainder term in the Taylor series (third derivative):

The third derivative and calculating the error isn't explicitly done here, but you can compute it using

R2(x)=f(c)3!x3R_2(x) = \frac{f'''(c)}{3!} x^3

where cc is between 0 and xx. You would need f(x)f'''(x) for a precise bound.

Once you have the calculation, you'll get an approximation for 103\sqrt{103} and can estimate the error.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Taylor Series
Derivatives
Polynomial Approximation

Formulas

f(x) = f(0) + f'(0)x + f''(0)/2! x^2 + ...
f(x) = (1 + x/2)^(1/2)
f'(x) = (1 + x/2)^(-1/2) * (1/2)
f''(x) = -1/16 (1 + x/2)^(-3/2)
T_2(x) = 1 + (1/4)x - (1/32)x^2

Theorems

Taylor Series Theorem
Error Estimation via Remainder Term

Suitable Grade Level

Grades 11-12