Math Problem Statement

Find the limit \( \lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^x \) and differentiate the function \( y = \ln^3{x} \).

Solution

Here are the problems from the image:

Question №4

Find the limit:
limx(1+1x)x\lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^x

Question №5

Find the derivative of the function:
y=ln3xy = \ln^3{x}


Solutions

Solution to Question №4:

The limit:
limx(1+1x)x\lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^x

This is a standard limit that results in the base of the natural logarithm ee:
limx(1+1x)x=e\lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^x = e

Thus, the answer is:
e\boxed{e}


Solution to Question №5:

To find the derivative of y=ln3xy = \ln^3{x}, we apply the chain rule. Rewrite the function:
y=(lnx)3y = (\ln{x})^3

The derivative is:
dydx=3(lnx)2ddx(lnx)\frac{dy}{dx} = 3 (\ln{x})^2 \cdot \frac{d}{dx}(\ln{x})

The derivative of lnx\ln{x} is 1x\frac{1}{x}. Therefore:
dydx=3(lnx)21x\frac{dy}{dx} = 3 (\ln{x})^2 \cdot \frac{1}{x}

Simplifying:
dydx=3(lnx)2x\frac{dy}{dx} = \frac{3 (\ln{x})^2}{x}

Thus, the derivative is:
3(lnx)2x\boxed{\frac{3 (\ln{x})^2}{x}}


Do you need further clarification on any step? Here are 5 related questions for practice:

  1. Evaluate limx(1+kx)x\lim_{x \to \infty} \left(1 + \frac{k}{x}\right)^x where kk is a constant.
  2. Differentiate y=ln4xy = \ln^4{x}.
  3. Prove that limx(1+1x)x+1=e\lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^{x+1} = e.
  4. Find the derivative of y=x2lnxy = x^2 \ln{x}.
  5. Find the second derivative of y=lnxy = \ln{x}.

Tip:

The limit (1+1x)x\left(1 + \frac{1}{x}\right)^x is a fundamental result that defines the constant ee. Understanding it is key for exponential and logarithmic growth analysis.

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Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Logarithmic Functions

Formulas

Standard limit: \( \lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^x = e \)
Derivative of power of a function: \( \frac{d}{dx}[u^n] = n u^{n-1} \cdot u' \)
Derivative of natural logarithm: \( \frac{d}{dx}[\ln{x}] = \frac{1}{x} \)

Theorems

Fundamental Limit Theorem
Chain Rule for Differentiation

Suitable Grade Level

Grades 10-12