2. \(\int_1^e x^4 \ln x \, dx\)






Answer is: option2

\(\frac{4e^5 + 1}{25}\)

Solution:

We are tasked with solving the definite integral:

\[ \int_1^e x^4 \ln(x) \, dx \]

Step 1: Differentiate and Integrate

We choose \( u = \ln(x) \) and \( dv = x^4 \, dx \).

Differentiate \( u \) and integrate \( dv \):

\[ u = \ln(x) \quad \Rightarrow \quad du = \frac{1}{x} \, dx \]

\[ dv = x^4 \, dx \quad \Rightarrow \quad v = \frac{x^5}{5} \]

Step 2: Apply the Integration by Parts Formula

Now, apply the integration by parts formula:

\[ \int_1^e x^4 \ln(x) \, dx = \left[ \ln(x) \cdot \frac{x^5}{5} \right]_1^e - \int_1^e \frac{x^5}{5} \cdot \frac{1}{x} \, dx \]

Step 3: Simplify the Expression

Simplify the remaining integral:

\[ \int_1^e \frac{x^5}{5} \cdot \frac{1}{x} \, dx = \frac{1}{5} \int_1^e x^4 \, dx \]

Now, compute \( \int_1^e x^4 \, dx \):

\[ \int_1^e x^4 \, dx = \left[ \frac{x^5}{5} \right]_1^e = \frac{e^5}{5} - \frac{1}{5} \]

So, we have:

\[ \int_1^e \frac{x^5}{5} \cdot \frac{1}{x} \, dx = \frac{1}{5} \left( \frac{e^5}{5} - \frac{1}{5} \right) = \frac{e^5 - 1}{25} \]

Step 4: Combine the Results

Now, combine the results:

\[ \int_1^e x^4 \ln(x) \, dx = \left[ \frac{e^5}{5} \ln(e) - \frac{1}{5} \ln(1) \right] - \frac{e^5 - 1}{25} \]

Since \( \ln(e) = 1 \) and \( \ln(1) = 0 \), this simplifies to:

\[ \int_1^e x^4 \ln(x) \, dx = \frac{e^5}{5} - \frac{e^5 - 1}{25} \]

Step 5: Simplify the Final Expression

Now, simplify the expression:

\[ \frac{e^5}{5} - \frac{e^5 - 1}{25} = \frac{5e^5}{25} - \frac{e^5 - 1}{25} = \frac{5e^5 - e^5 + 1}{25} = \frac{4e^5 + 1}{25} \]

Final Answer

\[ \frac{4e^5 + 1}{25} \]

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