Math Problem Statement

תפתור לי

Find the Taylor series expansion of the function \( f(x) = \sqrt{1+x} \) around \( x_0 = 0 \).

Solution

The problem involves finding the Taylor series expansion for the function f(x)=1+xf(x) = \sqrt{1+x} around x0=0x_0 = 0. Let's solve step by step:

Step 1: The Taylor series formula

The Taylor series for a function f(x)f(x) around x0=0x_0 = 0 is given by: f(x)=f(0)+f(0)x+f(0)2!x2+f(3)(0)3!x3+f(x) = f(0) + f'(0)x + \frac{f''(0)}{2!}x^2 + \frac{f^{(3)}(0)}{3!}x^3 + \cdots

Step 2: Compute derivatives of f(x)f(x)

The function is f(x)=1+x=(1+x)1/2f(x) = \sqrt{1+x} = (1+x)^{1/2}.

  1. Zeroth derivative (function itself): f(x)=(1+x)1/2,f(0)=1=1f(x) = (1+x)^{1/2}, \quad f(0) = \sqrt{1} = 1

  2. First derivative: f(x)=12(1+x)1/2,f(0)=12f'(x) = \frac{1}{2}(1+x)^{-1/2}, \quad f'(0) = \frac{1}{2}

  3. Second derivative: f(x)=14(1+x)3/2,f(0)=14f''(x) = \frac{-1}{4}(1+x)^{-3/2}, \quad f''(0) = \frac{-1}{4}

  4. Third derivative: f(3)(x)=38(1+x)5/2,f(3)(0)=38f^{(3)}(x) = \frac{3}{8}(1+x)^{-5/2}, \quad f^{(3)}(0) = \frac{3}{8}

Step 3: Substitute into the Taylor series

Using the derivatives, the Taylor expansion becomes: f(x)=f(0)+f(0)x+f(0)2!x2+f(3)(0)3!x3+f(x) = f(0) + f'(0)x + \frac{f''(0)}{2!}x^2 + \frac{f^{(3)}(0)}{3!}x^3 + \cdots

Substitute the computed values: f(x)=1+12x14x22+38x36f(x) = 1 + \frac{1}{2}x - \frac{1}{4}\frac{x^2}{2} + \frac{3}{8}\frac{x^3}{6}

Simplify each term: f(x)=1+12x18x2+116x3f(x) = 1 + \frac{1}{2}x - \frac{1}{8}x^2 + \frac{1}{16}x^3

Final Answer:

The Taylor expansion is: f(x)=1+12x18x2+116x3f(x) = 1 + \frac{1}{2}x - \frac{1}{8}x^2 + \frac{1}{16}x^3

Let me know if you want more details about any step or further clarifications! Here are 5 related questions to expand your understanding:

  1. What is the general formula for the nn-th derivative of (1+x)n(1+x)^n?
  2. How can we determine the radius of convergence for this Taylor series?
  3. Why do we divide by n!n! in the Taylor series formula?
  4. How does the remainder term in the Taylor series affect the approximation?
  5. Can you approximate 1.1\sqrt{1.1} using this Taylor series?

Tip: For Taylor series, always compute a few derivatives carefully to ensure accuracy!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Taylor Series
Calculus
Polynomial Approximations

Formulas

Taylor series formula: \( f(x) = f(0) + f'(0)x + \frac{f''(0)}{2!}x^2 + \cdots \)
Derivative of \( \sqrt{1+x} \): \( f'(x) = \frac{1}{2}(1+x)^{-1/2} \)

Theorems

Taylor's Theorem
Power Series Expansion

Suitable Grade Level

Grade 12 or College Level