Calculus Examples

$\int_{1}^{e} x^{3} \ln (x) d x$

Step 1

Integrate by parts using the formula $\int u d v = u v - \int v d u$ , where $u = \ln (x)$ and $d v = x^{3}$ .

$\ln (x) (\frac{1}{4} x^{4})]_{1}^{e} - \int_{1}^{e} \frac{1}{4} x^{4} \frac{1}{x} d x$

Step 2

Simplify.

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Step 2.1

Combine $\frac{1}{4}$ and $x^{4}$ .

$\ln (x) \frac{x^{4}}{4}]_{1}^{e} - \int_{1}^{e} \frac{1}{4} x^{4} \frac{1}{x} d x$

Step 2.2

Combine $\ln (x)$ and $\frac{x^{4}}{4}$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - \int_{1}^{e} \frac{1}{4} x^{4} \frac{1}{x} d x$

Step 3

Since $\frac{1}{4}$ is constant with respect to $x$ , move $\frac{1}{4}$ out of the integral.

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} x^{4} \frac{1}{x} d x)$

Step 4

Simplify.

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Step 4.1

Combine $x^{4}$ and $\frac{1}{x}$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} \frac{x^{4}}{x} d x)$

Step 4.2

Cancel the common factor of $x^{4}$ and $x$ .

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Step 4.2.1

Factor $x$ out of $x^{4}$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} \frac{x \cdot x^{3}}{x} d x)$

Step 4.2.2

Cancel the common factors.

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Step 4.2.2.1

Raise $x$ to the power of $1$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} \frac{x \cdot x^{3}}{x^{1}} d x)$

Step 4.2.2.2

Factor $x$ out of $x^{1}$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} \frac{x \cdot x^{3}}{x \cdot 1} d x)$

Step 4.2.2.3

Cancel the common factor.

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} \frac{x \cdot x^{3}}{x \cdot 1} d x)$

Step 4.2.2.4

Rewrite the expression.

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} \frac{x^{3}}{1} d x)$

Step 4.2.2.5

Divide $x^{3}$ by $1$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - (\frac{1}{4} \int_{1}^{e} x^{3} d x)$

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - \frac{1}{4} \int_{1}^{e} x^{3} d x$

Step 5

By the Power Rule, the integral of $x^{3}$ with respect to $x$ is $\frac{1}{4} x^{4}$ .

$\frac{\ln (x) x^{4}}{4}]_{1}^{e} - \frac{1}{4} \frac{1}{4} x^{4}]_{1}^{e}$

Step 6

Simplify the answer.

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Step 6.1

Evaluate $\frac{\ln (x) x^{4}}{4}$ at $e$ and at $1$ .

$(\frac{\ln (e) e^{4}}{4}) - \frac{\ln (1) \cdot 1^{4}}{4} - \frac{1}{4} \frac{1}{4} x^{4}]_{1}^{e}$

Step 6.2

Evaluate $\frac{1}{4} x^{4}$ at $e$ and at $1$ .

$(\frac{\ln (e) e^{4}}{4}) - \frac{\ln (1) \cdot 1^{4}}{4} - \frac{1}{4} ((\frac{1}{4} e^{4}) - \frac{1}{4} \cdot 1^{4})$

Step 6.3

One to any power is one.

$\frac{\ln (e) e^{4}}{4} - \frac{\ln (1) \cdot 1}{4} - \frac{1}{4} ((\frac{1}{4} e^{4}) - \frac{1}{4} \cdot 1^{4})$

Step 6.4

Multiply $\ln (1)$ by $1$ .

$\frac{\ln (e) e^{4}}{4} - \frac{\ln (1)}{4} - \frac{1}{4} ((\frac{1}{4} e^{4}) - \frac{1}{4} \cdot 1^{4})$

Step 6.5

Combine $\frac{1}{4}$ and $e^{4}$ .

$\frac{\ln (e) e^{4}}{4} - \frac{\ln (1)}{4} - \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4} \cdot 1^{4})$

Step 6.6

One to any power is one.

$\frac{\ln (e) e^{4}}{4} - \frac{\ln (1)}{4} - \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4} \cdot 1)$

Step 6.7

Multiply $- 1$ by $1$ .

$\frac{\ln (e) e^{4}}{4} - \frac{\ln (1)}{4} - \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4})$

Step 6.8

Simplify.

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Step 6.8.1

To write $- \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4})$ as a fraction with a common denominator, multiply by $\frac{4}{4}$ .

$\frac{\ln (e) e^{4}}{4} - \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4}) \cdot \frac{4}{4} - \frac{\ln (1)}{4}$

Step 6.8.2

Combine $- \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4})$ and $\frac{4}{4}$ .

$\frac{\ln (e) e^{4}}{4} + \frac{- \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4}) \cdot 4}{4} - \frac{\ln (1)}{4}$

Step 6.8.3

Combine the numerators over the common denominator.

$\frac{\ln (e) e^{4} - \frac{1}{4} (\frac{e^{4}}{4} - \frac{1}{4}) \cdot 4}{4} - \frac{\ln (1)}{4}$

Step 6.8.4

Multiply $4$ by $- 1$ .

$\frac{\ln (e) e^{4} - 4 (\frac{1}{4}) (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 6.8.5

Combine $- 4$ and $\frac{1}{4}$ .

$\frac{\ln (e) e^{4} + \frac{- 4}{4} (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 6.8.6

Cancel the common factor of $- 4$ and $4$ .

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Step 6.8.6.1

Factor $4$ out of $- 4$ .

$\frac{\ln (e) e^{4} + \frac{4 \cdot - 1}{4} (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 6.8.6.2

Cancel the common factors.

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Step 6.8.6.2.1

Factor $4$ out of $4$ .

$\frac{\ln (e) e^{4} + \frac{4 \cdot - 1}{4 (1)} (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 6.8.6.2.2

Cancel the common factor.

$\frac{\ln (e) e^{4} + \frac{4 \cdot - 1}{4 \cdot 1} (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 6.8.6.2.3

Rewrite the expression.

$\frac{\ln (e) e^{4} + \frac{- 1}{1} (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 6.8.6.2.4

Divide $- 1$ by $1$ .

$\frac{\ln (e) e^{4} - (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Step 7

The result can be shown in multiple forms.

Exact Form:

$\frac{\ln (e) e^{4} - (\frac{e^{4}}{4} - \frac{1}{4})}{4} - \frac{\ln (1)}{4}$

Decimal Form:

$10.29965313 \dots$