Pre-Algebra Examples

$\frac{\frac{5 + x^{2}}{7 \sqrt{x}} - 7 x \sqrt{x}}{{(5 + x^{2})}^{2}}$

Step 1

Find where the expression $\frac{\sqrt{x} (5 - 48 x^{2})}{7 x {(5 + x^{2})}^{2}}$ is undefined.

$x \leq 0$

Step 2

Since $\frac{\sqrt{x} (5 - 48 x^{2})}{7 x {(5 + x^{2})}^{2}}$ $\to$ $\infty$ as $x$ $\to$ $0$ from the left and $\frac{\sqrt{x} (5 - 48 x^{2})}{7 x {(5 + x^{2})}^{2}}$ $\to$ $\infty$ as $x$ $\to$ $0$ from the right, then $x = 0$ is a vertical asymptote.

$x = 0$

Step 3

Evaluate $lim_{x \to \infty} \frac{\sqrt{x} (5 - 48 x^{2})}{7 x {(5 + x^{2})}^{2}}$ to find the horizontal asymptote.

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Step 3.1

Reduce.

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Step 3.1.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{x}$ as $x^{\frac{1}{2}}$ .

$lim_{x \to \infty} \frac{x^{\frac{1}{2}} (5 - 48 x^{2})}{7 x {(5 + x^{2})}^{2}}$

Step 3.1.2

Factor $x$ out of $x^{\frac{1}{2}} (5 - 48 x^{2})$ .

$lim_{x \to \infty} \frac{x (x^{- \frac{1}{2}} (5 - 48 x^{2}))}{7 x {(5 + x^{2})}^{2}}$

Step 3.1.3

Cancel the common factors.

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Step 3.1.3.1

Factor $x$ out of $7 x {(5 + x^{2})}^{2}$ .

$lim_{x \to \infty} \frac{x (x^{- \frac{1}{2}} (5 - 48 x^{2}))}{x (7 {(5 + x^{2})}^{2})}$

Step 3.1.3.2

Cancel the common factor.

$lim_{x \to \infty} \frac{x (x^{- \frac{1}{2}} (5 - 48 x^{2}))}{x (7 {(5 + x^{2})}^{2})}$

Step 3.1.3.3

Rewrite the expression.

$lim_{x \to \infty} \frac{x^{- \frac{1}{2}} (5 - 48 x^{2})}{7 {(5 + x^{2})}^{2}}$

Step 3.1.4

Move $x^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$lim_{x \to \infty} \frac{5 - 48 x^{2}}{7 {(5 + x^{2})}^{2} x^{\frac{1}{2}}}$

Step 3.2

Move the term $\frac{1}{7}$ outside of the limit because it is constant with respect to $x$ .

$\frac{1}{7} lim_{x \to \infty} \frac{5 - 48 x^{2}}{{(5 + x^{2})}^{2} x^{\frac{1}{2}}}$

Step 3.3

Rewrite $x^{\frac{1}{2}}$ as $\sqrt{x}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{5 - 48 x^{2}}{{(5 + x^{2})}^{2} \sqrt{x}}$

Step 3.4

Reorder factors in ${(5 + x^{2})}^{2} \sqrt{x}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{5 - 48 x^{2}}{\sqrt{x} {(5 + x^{2})}^{2}}$

Step 3.5

Divide the numerator and denominator by the highest power of $x$ in the denominator.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} + \frac{- 48 x^{2}}{x^{4}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6

Simplify terms.

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Step 3.6.1

Simplify each term.

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Step 3.6.1.1

Cancel the common factor of $x^{2}$ and $x^{4}$ .

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Step 3.6.1.1.1

Factor $x^{2}$ out of $- 48 x^{2}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} + \frac{x^{2} \cdot - 48}{x^{4}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6.1.1.2

Cancel the common factors.

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Step 3.6.1.1.2.1

Factor $x^{2}$ out of $x^{4}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} + \frac{x^{2} \cdot - 48}{x^{2} x^{2}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6.1.1.2.2

Cancel the common factor.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} + \frac{x^{2} \cdot - 48}{x^{2} x^{2}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6.1.1.2.3

Rewrite the expression.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} + \frac{- 48}{x^{2}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6.1.2

Move the negative in front of the fraction.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6.2

Reduce the expression by cancelling the common factors.

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Step 3.6.2.1

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

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Step 3.6.2.1.1

Cancel the common factor.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} {(\frac{5}{x^{2}} + \frac{x^{2}}{x^{2}})}^{2}}$

Step 3.6.2.1.2

Rewrite the expression.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} {(\frac{5}{x^{2}} + 1)}^{2}}$

Step 3.6.2.2

Rewrite ${(\frac{5}{x^{2}} + 1)}^{2}$ as $(\frac{5}{x^{2}} + 1) (\frac{5}{x^{2}} + 1)$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5}{x^{2}} + 1) (\frac{5}{x^{2}} + 1)}$

Step 3.7

Expand $(\frac{5}{x^{2}} + 1) (\frac{5}{x^{2}} + 1)$ using the FOIL Method.

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Step 3.7.1

Apply the distributive property.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5}{x^{2}} (\frac{5}{x^{2}} + 1) + 1 (\frac{5}{x^{2}} + 1))}$

Step 3.7.2

Apply the distributive property.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5}{x^{2}} \cdot \frac{5}{x^{2}} + \frac{5}{x^{2}} \cdot 1 + 1 (\frac{5}{x^{2}} + 1))}$

Step 3.7.3

Apply the distributive property.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5}{x^{2}} \cdot \frac{5}{x^{2}} + \frac{5}{x^{2}} \cdot 1 + 1 \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8

Simplify and combine like terms.

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Step 3.8.1

Simplify each term.

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Step 3.8.1.1

Combine.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5 \cdot 5}{x^{2} x^{2}} + \frac{5}{x^{2}} \cdot 1 + 1 \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8.1.2

Multiply $x^{2}$ by $x^{2}$ by adding the exponents.

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Step 3.8.1.2.1

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5 \cdot 5}{x^{2 + 2}} + \frac{5}{x^{2}} \cdot 1 + 1 \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8.1.2.2

Add $2$ and $2$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{5 \cdot 5}{x^{4}} + \frac{5}{x^{2}} \cdot 1 + 1 \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8.1.3

Multiply $5$ by $5$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + \frac{5}{x^{2}} \cdot 1 + 1 \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8.1.4

Multiply $\frac{5}{x^{2}}$ by $1$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + \frac{5}{x^{2}} + 1 \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8.1.5

Multiply $\frac{5}{x^{2}}$ by $1$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + \frac{5}{x^{2}} + \frac{5}{x^{2}} + 1 \cdot 1)}$

Step 3.8.1.6

Multiply $1$ by $1$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + \frac{5}{x^{2}} + \frac{5}{x^{2}} + 1)}$

Step 3.8.2

Add $\frac{5}{x^{2}}$ and $\frac{5}{x^{2}}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + 2 \frac{5}{x^{2}} + 1)}$

Step 3.9

Multiply $2 \frac{5}{x^{2}}$ .

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Step 3.9.1

Combine $2$ and $\frac{5}{x^{2}}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + \frac{2 \cdot 5}{x^{2}} + 1)}$

Step 3.9.2

Multiply $2$ by $5$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} (\frac{25}{x^{4}} + \frac{10}{x^{2}} + 1)}$

Step 3.10

Apply the distributive property.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\sqrt{x} \frac{25}{x^{4}} + \sqrt{x} \frac{10}{x^{2}} + \sqrt{x} \cdot 1}$

Step 3.11

Simplify.

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Step 3.11.1

Combine $\sqrt{x}$ and $\frac{25}{x^{4}}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\frac{\sqrt{x} \cdot 25}{x^{4}} + \sqrt{x} \frac{10}{x^{2}} + \sqrt{x} \cdot 1}$

Step 3.11.2

Combine $\sqrt{x}$ and $\frac{10}{x^{2}}$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\frac{\sqrt{x} \cdot 25}{x^{4}} + \frac{\sqrt{x} \cdot 10}{x^{2}} + \sqrt{x} \cdot 1}$

Step 3.11.3

Multiply $\sqrt{x}$ by $1$ .

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\frac{\sqrt{x} \cdot 25}{x^{4}} + \frac{\sqrt{x} \cdot 10}{x^{2}} + \sqrt{x}}$

Step 3.12

Simplify each term.

$\frac{1}{7} lim_{x \to \infty} \frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\frac{25 \sqrt{x}}{x^{4}} + \frac{10 \sqrt{x}}{x^{2}} + \sqrt{x}}$

Step 3.13

Since its numerator approaches a real number while its denominator is unbounded, the fraction $\frac{\frac{5}{x^{4}} - \frac{48}{x^{2}}}{\frac{25 \sqrt{x}}{x^{4}} + \frac{10 \sqrt{x}}{x^{2}} + \sqrt{x}}$ approaches $0$ .

$\frac{1}{7} \cdot 0$

Step 3.14

Multiply $\frac{1}{7}$ by $0$ .

$0$

Step 4

List the horizontal asymptotes:

$y = 0$

Step 5

Use polynomial division to find the oblique asymptotes. Because this expression contains a radical, polynomial division cannot be performed.

Cannot Find Oblique Asymptotes

Step 6

This is the set of all asymptotes.

Vertical Asymptotes: $x = 0$

Horizontal Asymptotes: $y = 0$

Cannot Find Oblique Asymptotes

Step 7