Precalculus Examples

f (x) = \frac{1}{x - 5}

$f (x) = \frac{1}{x - 5}$

Step 1

Find where the expression

\frac{1}{x - 5}

$\frac{1}{x - 5}$ is undefined.

x = 5

$x = 5$

Step 2

Consider the rational function

R (x) = \frac{a x^{n}}{b x^{m}}

$R (x) = \frac{a x^{n}}{b x^{m}}$ where

n

$n$ is the degree of the numerator and

m

$m$ is the degree of the denominator.

1. If

n < m

$n < m$ , then the x-axis,

y = 0

$y = 0$ , is the horizontal asymptote.

2. If

n = m

$n = m$ , then the horizontal asymptote is the line

y = \frac{a}{b}

$y = \frac{a}{b}$ .

3. If

n > m

$n > m$ , then there is no horizontal asymptote (there is an oblique asymptote).

Step 3

Find

n

$n$ and

m

$m$ .

n = 0

$n = 0$

m = 1

$m = 1$

Step 4

Since

n < m

$n < m$ , the x-axis,

y = 0

$y = 0$ , is the horizontal asymptote.

y = 0

$y = 0$

Step 5

There is no oblique asymptote because the degree of the numerator is less than or equal to the degree of the denominator.

No Oblique Asymptotes

Step 6

This is the set of all asymptotes.

Vertical Asymptotes:

x = 5

$x = 5$

Horizontal Asymptotes:

y = 0

$y = 0$

No Oblique Asymptotes

Step 7

f (x) = \frac{1}{x - 5}

$f (x) = \frac{1}{x - 5}$

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