Math Problem Statement

\lim_(x->0^(+))x^(sinx)

Solution

To evaluate the limit limx0+xsinx\lim_{x \to 0^+} x^{\sin x}, let's proceed step-by-step:

Step 1: Rewrite xsinxx^{\sin x}

The term xsinxx^{\sin x} can be rewritten using the exponential and logarithmic identities: xsinx=esinxlnx.x^{\sin x} = e^{\sin x \cdot \ln x}. Thus, the problem reduces to finding: limx0+esinxlnx.\lim_{x \to 0^+} e^{\sin x \cdot \ln x}.

Step 2: Analyze the exponent sinxlnx\sin x \cdot \ln x

We now focus on evaluating: limx0+sinxlnx.\lim_{x \to 0^+} \sin x \cdot \ln x.

  1. As x0+x \to 0^+, sinx0\sin x \to 0.
  2. lnx\ln x \to -\infty as x0+x \to 0^+.
  3. The product sinxlnx\sin x \cdot \ln x involves the interplay between a term approaching 0 (sinx\sin x) and a term approaching -\infty (lnx\ln x).

Step 3: Approximation for sinx\sin x near 0

For small xx, sinxx\sin x \approx x. Substituting this approximation: sinxlnxxlnx.\sin x \cdot \ln x \approx x \cdot \ln x.

Now, analyze limx0+xlnx\lim_{x \to 0^+} x \cdot \ln x:

  • Let y=xlnxy = x \cdot \ln x. Rewrite it as: y=lnx1/x.y = \frac{\ln x}{1/x}.
  • This is a \frac{-\infty}{\infty} indeterminate form, so we apply L'Hôpital's Rule: limx0+lnx1/x=limx0+ddx(lnx)ddx(1/x)=limx0+1/x1/x2=limx0+x=0.\lim_{x \to 0^+} \frac{\ln x}{1/x} = \lim_{x \to 0^+} \frac{\frac{d}{dx}(\ln x)}{\frac{d}{dx}(1/x)} = \lim_{x \to 0^+} \frac{1/x}{-1/x^2} = \lim_{x \to 0^+} -x = 0.

Thus, limx0+xlnx=0\lim_{x \to 0^+} x \cdot \ln x = 0, and consequently: limx0+sinxlnx=0.\lim_{x \to 0^+} \sin x \cdot \ln x = 0.

Step 4: Exponentiation

Using the result from Step 3: limx0+esinxlnx=e0=1.\lim_{x \to 0^+} e^{\sin x \cdot \ln x} = e^0 = 1.

Final Answer:

limx0+xsinx=1.\lim_{x \to 0^+} x^{\sin x} = 1.


Would you like further clarification or a visual explanation? Here are some related questions:

  1. How does xlnxx \ln x behave as x0+x \to 0^+?
  2. Why is sinxx\sin x \approx x a valid approximation for small xx?
  3. How does L'Hôpital's Rule apply in indeterminate forms like ×0-\infty \times 0?
  4. Can xsinxx^{\sin x} ever exceed 1 near x=0x = 0?
  5. What are the implications of this limit in calculus or real-world contexts?

Tip: When dealing with limits involving exponentials and logarithms, rewriting the expression in terms of eue^u often simplifies the problem.

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Math Problem Analysis

Mathematical Concepts

Limits
Exponential Functions
Logarithms
Trigonometry

Formulas

x^{\sin x} = e^{\sin x \cdot \ln x}
L'Hopital's Rule

Theorems

L'Hopital's Rule

Suitable Grade Level

Grades 11-12