Math Problem Statement

Evaluate the double integral: ∫₀¹ ∫₁ᵉˣ (x/y) dy dx

Solution

The double integral to evaluate is:

0111exxydydx\int_{0}^{11} \int_{1}^{e^x} \frac{x}{y} \, dy \, dx

Step-by-Step Solution:

  1. Inner Integral (with respect to yy):

    The inner integral is:

    1exxydy\int_{1}^{e^x} \frac{x}{y} \, dy

    Since xy\frac{x}{y} is a simple function in yy, we can integrate it easily:

    xydy=xln(y)\int \frac{x}{y} \, dy = x \ln(y)

    Now, apply the limits of integration y=1y = 1 to y=exy = e^x:

    xln(ex)xln(1)x \ln(e^x) - x \ln(1)

    We know ln(ex)=x\ln(e^x) = x and ln(1)=0\ln(1) = 0, so this simplifies to:

    xxx0=x2x \cdot x - x \cdot 0 = x^2

    Therefore, the result of the inner integral is x2x^2.

  2. Outer Integral (with respect to xx):

    Now, the outer integral becomes:

    011x2dx\int_{0}^{11} x^2 \, dx

    The integral of x2x^2 is:

    x33\frac{x^3}{3}

    Apply the limits x=0x = 0 to x=11x = 11:

    1133033=13313\frac{11^3}{3} - \frac{0^3}{3} = \frac{1331}{3}

    Thus, the value of the double integral is:

    13313\boxed{\frac{1331}{3}}

Let me know if you'd like more details or have any questions! Here are some related questions to explore:

  1. How would the result change if the limits of integration for yy were different?
  2. What is the significance of logarithmic functions in integration?
  3. How does changing the exponent in exe^x affect the double integral?
  4. Can this integral be solved using polar coordinates?
  5. How would you approach solving a triple integral involving a similar function?

Tip: When working with nested integrals, always handle one variable at a time, simplifying before proceeding to the next integration.

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Math Problem Analysis

Mathematical Concepts

Calculus
Double Integrals
Logarithmic Functions

Formulas

∫₁ᵉˣ (x/y) dy = x ln(y)
∫ x² dx = x³/3

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

University Level - Calculus II