Calculus Examples

$lim_{x \to \infty} \frac{x^{2} - 5 x}{2 x^{3} + x^{2} - 1}$

Step 1

Divide the numerator and denominator by the highest power of $x$ in the denominator, which is $x^{3}$ .

$lim_{x \to \infty} \frac{\frac{x^{2}}{x^{3}} + \frac{- 5 x}{x^{3}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2

Evaluate the limit.

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Step 2.1

Simplify each term.

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Step 2.1.1

Cancel the common factor of $x^{2}$ and $x^{3}$ .

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Step 2.1.1.1

Multiply by $1$ .

$lim_{x \to \infty} \frac{\frac{x^{2} \cdot 1}{x^{3}} + \frac{- 5 x}{x^{3}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.1.2

Cancel the common factors.

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Step 2.1.1.2.1

Factor $x^{2}$ out of $x^{3}$ .

$lim_{x \to \infty} \frac{\frac{x^{2} \cdot 1}{x^{2} x} + \frac{- 5 x}{x^{3}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.1.2.2

Cancel the common factor.

$lim_{x \to \infty} \frac{\frac{x^{2} \cdot 1}{x^{2} x} + \frac{- 5 x}{x^{3}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.1.2.3

Rewrite the expression.

$lim_{x \to \infty} \frac{\frac{1}{x} + \frac{- 5 x}{x^{3}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.2

Cancel the common factor of $x$ and $x^{3}$ .

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Step 2.1.2.1

Factor $x$ out of $- 5 x$ .

$lim_{x \to \infty} \frac{\frac{1}{x} + \frac{x \cdot - 5}{x^{3}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.2.2

Cancel the common factors.

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Step 2.1.2.2.1

Factor $x$ out of $x^{3}$ .

$lim_{x \to \infty} \frac{\frac{1}{x} + \frac{x \cdot - 5}{x \cdot x^{2}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.2.2.2

Cancel the common factor.

$lim_{x \to \infty} \frac{\frac{1}{x} + \frac{x \cdot - 5}{x \cdot x^{2}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.2.2.3

Rewrite the expression.

$lim_{x \to \infty} \frac{\frac{1}{x} + \frac{- 5}{x^{2}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.1.3

Move the negative in front of the fraction.

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.2

Simplify each term.

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Step 2.2.1

Cancel the common factor of $x^{3}$ .

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Step 2.2.1.1

Cancel the common factor.

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{\frac{2 x^{3}}{x^{3}} + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.2.1.2

Divide $2$ by $1$ .

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{2 + \frac{x^{2}}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.2.2

Cancel the common factor of $x^{2}$ and $x^{3}$ .

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Step 2.2.2.1

Multiply by $1$ .

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{2 + \frac{x^{2} \cdot 1}{x^{3}} - \frac{1}{x^{3}}}$

Step 2.2.2.2

Cancel the common factors.

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Step 2.2.2.2.1

Factor $x^{2}$ out of $x^{3}$ .

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{2 + \frac{x^{2} \cdot 1}{x^{2} x} - \frac{1}{x^{3}}}$

Step 2.2.2.2.2

Cancel the common factor.

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{2 + \frac{x^{2} \cdot 1}{x^{2} x} - \frac{1}{x^{3}}}$

Step 2.2.2.2.3

Rewrite the expression.

$lim_{x \to \infty} \frac{\frac{1}{x} - \frac{5}{x^{2}}}{2 + \frac{1}{x} - \frac{1}{x^{3}}}$

Step 2.3

Split the limit using the Limits Quotient Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} \frac{1}{x} - \frac{5}{x^{2}}}{lim_{x \to \infty} 2 + \frac{1}{x} - \frac{1}{x^{3}}}$

Step 2.4

Split the limit using the Sum of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} \frac{1}{x} - lim_{x \to \infty} \frac{5}{x^{2}}}{lim_{x \to \infty} 2 + \frac{1}{x} - \frac{1}{x^{3}}}$

Step 3

Since its numerator approaches a real number while its denominator is unbounded, the fraction $\frac{1}{x}$ approaches $0$ .

$\frac{0 - lim_{x \to \infty} \frac{5}{x^{2}}}{lim_{x \to \infty} 2 + \frac{1}{x} - \frac{1}{x^{3}}}$

Step 4

Move the term $5$ outside of the limit because it is constant with respect to $x$ .

$\frac{0 - 5 lim_{x \to \infty} \frac{1}{x^{2}}}{lim_{x \to \infty} 2 + \frac{1}{x} - \frac{1}{x^{3}}}$

Step 5

Since its numerator approaches a real number while its denominator is unbounded, the fraction $\frac{1}{x^{2}}$ approaches $0$ .

$\frac{0 - 5 \cdot 0}{lim_{x \to \infty} 2 + \frac{1}{x} - \frac{1}{x^{3}}}$

Step 6

Evaluate the limit.

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Step 6.1

Split the limit using the Sum of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{0 - 5 \cdot 0}{lim_{x \to \infty} 2 + lim_{x \to \infty} \frac{1}{x} - lim_{x \to \infty} \frac{1}{x^{3}}}$

Step 6.2

Evaluate the limit of $2$ which is constant as $x$ approaches $\infty$ .

$\frac{0 - 5 \cdot 0}{2 + lim_{x \to \infty} \frac{1}{x} - lim_{x \to \infty} \frac{1}{x^{3}}}$

Step 7

Since its numerator approaches a real number while its denominator is unbounded, the fraction $\frac{1}{x}$ approaches $0$ .

$\frac{0 - 5 \cdot 0}{2 + 0 - lim_{x \to \infty} \frac{1}{x^{3}}}$

Step 8

Since its numerator approaches a real number while its denominator is unbounded, the fraction $\frac{1}{x^{3}}$ approaches $0$ .

$\frac{0 - 5 \cdot 0}{2 + 0 - 0}$

Step 9

Simplify the answer.

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Step 9.1

Simplify the numerator.

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Step 9.1.1

Multiply $- 5$ by $0$ .

$\frac{0 + 0}{2 + 0 - 0}$

Step 9.1.2

Add $0$ and $0$ .

$\frac{0}{2 + 0 - 0}$

Step 9.2

Simplify the denominator.

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Step 9.2.1

Multiply $- 1$ by $0$ .

$\frac{0}{2 + 0 + 0}$

Step 9.2.2

Add $2 + 0$ and $0$ .

$\frac{0}{2 + 0}$

Step 9.2.3

Add $2$ and $0$ .

$\frac{0}{2}$

Step 9.3

Divide $0$ by $2$ .

$0$