Math Problem Statement

find f'(x), f''(x) and f'''(x) for x\ln\left(x\right)

Solution

We are asked to find the first, second, and third derivatives of the function f(x)=xln(x)f(x) = x \ln(x).

Step 1: First Derivative f(x)f'(x)

We use the product rule to differentiate f(x)=xln(x)f(x) = x \ln(x).

The product rule states that: ddx[u(x)v(x)]=u(x)v(x)+u(x)v(x)\frac{d}{dx}[u(x)v(x)] = u'(x)v(x) + u(x)v'(x) Here, u(x)=xu(x) = x and v(x)=ln(x)v(x) = \ln(x).

Now, calculate their derivatives:

  • u(x)=ddx[x]=1u'(x) = \frac{d}{dx}[x] = 1
  • v(x)=ddx[ln(x)]=1xv'(x) = \frac{d}{dx}[\ln(x)] = \frac{1}{x}

Now, apply the product rule: f(x)=1ln(x)+x1x=ln(x)+1f'(x) = 1 \cdot \ln(x) + x \cdot \frac{1}{x} = \ln(x) + 1

Step 2: Second Derivative f(x)f''(x)

Now we differentiate f(x)=ln(x)+1f'(x) = \ln(x) + 1.

The derivative of ln(x)\ln(x) is 1x\frac{1}{x}, and the derivative of 1 is 0. So: f(x)=1xf''(x) = \frac{1}{x}

Step 3: Third Derivative f(x)f'''(x)

Finally, we differentiate f(x)=1xf''(x) = \frac{1}{x}.

The derivative of 1x\frac{1}{x} is 1x2-\frac{1}{x^2}. So: f(x)=1x2f'''(x) = -\frac{1}{x^2}

Summary:

f(x)=ln(x)+1f'(x) = \ln(x) + 1 f(x)=1xf''(x) = \frac{1}{x} f(x)=1x2f'''(x) = -\frac{1}{x^2}

Would you like further details on these steps or have any questions?

Here are 5 related questions you might consider:

  1. How does the product rule apply to more complex functions?
  2. What are the conditions for f(x)f'(x) to exist for logarithmic functions?
  3. Can the chain rule be used in differentiating xln(x)x \ln(x)?
  4. What happens to higher-order derivatives of xln(x)x \ln(x)?
  5. How do the properties of logarithms affect their derivatives?

Tip: When differentiating a product of two functions, always consider applying the product rule first to avoid mistakes!

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Product Rule
Higher-Order Derivatives

Formulas

Product Rule: \frac{d}{dx}[u(x)v(x)] = u'(x)v(x) + u(x)v'(x)
Derivative of ln(x): \frac{d}{dx}[\ln(x)] = \frac{1}{x}

Theorems

Product Rule for Differentiation
Basic Logarithmic Differentiation

Suitable Grade Level

Grades 11-12, College Calculus