Math Problem Statement

If \( f: \mathbb{R} \to \mathbb{R} \) is defined by \( f(x) = \begin{cases} e^{x/2} - 1, & x \leq 0 \\ \frac{1 - \cos x}{x}, & x > 0 \end{cases} \), what is the value of \( f'(0) \)?

Solution

To solve this problem, we need to find the derivative of f(x)f(x) at x=0x = 0, which is f(0)f'(0), given that:

\begin{cases} e^{x/2} - 1, & x \leq 0 \\ \frac{1 - \cos x}{x}, & x > 0 \end{cases}$$ ### Step-by-Step Solution 1. **Left-Hand Limit** (when $$x \to 0^-$$): Since $$x \leq 0$$ part of the function is $$f(x) = e^{x/2} - 1$$, let's calculate $$f'(0^-)$$: $$f'(x) = \frac{d}{dx}\left( e^{x/2} - 1 \right) = \frac{1}{2} e^{x/2}$$ Now, we calculate the limit as $$x \to 0^-$$: $$f'(0^-) = \frac{1}{2} e^{0/2} = \frac{1}{2}$$ 2. **Right-Hand Limit** (when $$x \to 0^+$$): For $$x > 0$$, $$f(x) = \frac{1 - \cos x}{x}$$. To find $$f'(0^+)$$, observe that as $$x \to 0$$, the function $$\frac{1 - \cos x}{x}$$ resembles the derivative of $$\sin^2(x/2) / x$$, which approaches zero. Thus, it is also $$\frac{1}{2}$$.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Differentiation
Piecewise Functions

Formulas

Derivative of \( e^{x/2} \)
Derivative of \( \frac{1 - \cos x}{x} \)

Theorems

Limit definition of derivative
Squeeze theorem

Suitable Grade Level

Undergraduate