Math Problem Statement

Evaluate the integral \( \int_{\sqrt{2}}^{1} \left( \frac{u^5}{4} - \frac{1}{u^3} \right) \, du \)

Solution

The given integral is:

21(u541u3)du\int_{\sqrt{2}}^{1} \left( \frac{u^5}{4} - \frac{1}{u^3} \right) \, du

Step 1: Break the integral into parts

21(u541u3)du=1421u5du211u3du\int_{\sqrt{2}}^{1} \left( \frac{u^5}{4} - \frac{1}{u^3} \right) \, du = \frac{1}{4} \int_{\sqrt{2}}^{1} u^5 \, du - \int_{\sqrt{2}}^{1} \frac{1}{u^3} \, du

Step 2: Solve each part of the integral

(a) First term: 14u5du\frac{1}{4} \int u^5 \, du

Using the power rule for integration: undu=un+1n+1,n1\int u^n \, du = \frac{u^{n+1}}{n+1}, \quad n \neq -1

Here, n=5n = 5: u5du=u66\int u^5 \, du = \frac{u^{6}}{6} So: 14u5du=14u66=u624\frac{1}{4} \int u^5 \, du = \frac{1}{4} \cdot \frac{u^{6}}{6} = \frac{u^{6}}{24}

(b) Second term: 1u3du\int \frac{1}{u^3} \, du

Rewrite 1u3\frac{1}{u^3} as u3u^{-3}: u3du=u3+13+1=u22=12u2\int u^{-3} \, du = \frac{u^{-3+1}}{-3+1} = \frac{u^{-2}}{-2} = -\frac{1}{2u^2}

Step 3: Combine results

The integral becomes: [ \int_{\sqrt{2}}^{1} \left( \frac{u^5}{4} - \frac{1}{u^3} \right) , du = \left[ \frac{u^6}{24} \right]{\sqrt{2}}^{1} - \left[ -\frac{1}{2u^2} \right]{\sqrt{2}}^{1} ]

Step 4: Evaluate definite integrals

(a) For u624\frac{u^6}{24}:

[u624]21=1624(2)624\left[ \frac{u^6}{24} \right]_{\sqrt{2}}^{1} = \frac{1^6}{24} - \frac{(\sqrt{2})^6}{24} =124(23)24=124824=724= \frac{1}{24} - \frac{(2^3)}{24} = \frac{1}{24} - \frac{8}{24} = -\frac{7}{24}

(b) For 12u2-\frac{1}{2u^2}:

[12u2]21=12(12)+12(2)2\left[ -\frac{1}{2u^2} \right]_{\sqrt{2}}^{1} = -\frac{1}{2(1^2)} + \frac{1}{2(\sqrt{2})^2} =12+12(2)=12+14=24+14=14= -\frac{1}{2} + \frac{1}{2(2)} = -\frac{1}{2} + \frac{1}{4} = -\frac{2}{4} + \frac{1}{4} = -\frac{1}{4}

Step 5: Combine results

The total integral is: 72414-\frac{7}{24} - \frac{1}{4} Convert 14-\frac{1}{4} to have a denominator of 24: 724624=1324-\frac{7}{24} - \frac{6}{24} = -\frac{13}{24}

Final Answer:

1324\boxed{-\frac{13}{24}}

Let me know if you would like more details or have any questions!


Related Questions:

  1. How do you apply the power rule to integrals?
  2. What are the common rules for definite integrals with fractional powers?
  3. How can substitution simplify similar integrals?
  4. What happens when n=1n = -1 in undu\int u^n \, du?
  5. How can this integral be solved using numerical methods instead of symbolic integration?

Tip:

Always double-check the limits of definite integrals, as switching the limits can change the sign of the result!

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Math Problem Analysis

Mathematical Concepts

Calculus
Definite Integrals
Power Rule for Integration

Formulas

Power rule for integration: \( \int u^n \, du = \frac{u^{n+1}}{n+1} \)
Simplification of \( \frac{1}{u^n} \) as \( u^{-n} \)

Theorems

Definite integral evaluation theorem

Suitable Grade Level

Grades 11-12, College Calculus I