Math Problem Statement

Evaluate.

Integral from 1 to e squared left parenthesis 3 x plus StartFraction 5 Over x EndFraction right parenthesis dx

Solution

We are tasked with evaluating the definite integral:

1e2(3x+5x)dx\int_{1}^{e^2} \left(3x + \frac{5}{x}\right) \, dx

Step 1: Break the integral into two separate terms

1e2(3x+5x)dx=1e23xdx+1e25xdx\int_{1}^{e^2} \left(3x + \frac{5}{x}\right) \, dx = \int_{1}^{e^2} 3x \, dx + \int_{1}^{e^2} \frac{5}{x} \, dx

Step 2: Evaluate each integral

  1. First term: 3xdx=3x22\int 3x \, dx = \frac{3x^2}{2} So, the definite integral becomes: [3x22]1e2=3(e2)223(1)22=3e4232\left[\frac{3x^2}{2}\right]_1^{e^2} = \frac{3(e^2)^2}{2} - \frac{3(1)^2}{2} = \frac{3e^4}{2} - \frac{3}{2}

  2. Second term: 5xdx=5lnx\int \frac{5}{x} \, dx = 5 \ln|x| The definite integral becomes: [5lnx]1e2=5ln(e2)5ln(1)\left[5 \ln|x|\right]_1^{e^2} = 5 \ln(e^2) - 5 \ln(1) Since ln(e2)=2\ln(e^2) = 2 and ln(1)=0\ln(1) = 0, this simplifies to: 5250=105 \cdot 2 - 5 \cdot 0 = 10

Step 3: Add the results

Combine the results from both terms: 3e4232+10\frac{3e^4}{2} - \frac{3}{2} + 10 Simplify: 3e42+172\frac{3e^4}{2} + \frac{17}{2}

Final Answer:

3e4+172\boxed{\frac{3e^4 + 17}{2}}

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Related Questions:

  1. How do you compute the definite integral step-by-step manually?
  2. What is the significance of breaking the integral into simpler terms?
  3. How does the natural logarithm property ln(e2)=2\ln(e^2) = 2 help simplify calculations?
  4. Can this be solved numerically to verify the result?
  5. How do definite integrals apply in real-world scenarios?

Tip:

Always split complex integrals into smaller terms to make calculations more manageable.

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Math Problem Analysis

Mathematical Concepts

Definite Integrals
Algebraic Simplification
Logarithmic Properties

Formulas

Integral of x: ∫x dx = x^2/2 + C
Integral of 1/x: ∫1/x dx = ln|x| + C
Definite Integral Formula: ∫[a, b] f(x) dx = F(b) - F(a)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12