Find the Asymptotes y=(2x^2+4x-1)/(x-1)

$y = \frac{2 x^{2} + 4 x - 1}{x - 1}$

Step 1

Find where the expression $\frac{2 x^{2} + 4 x - 1}{x - 1}$ is undefined.

$x = 1$

Step 2

Consider the rational function $R (x) = \frac{a x^{n}}{b x^{m}}$ where $n$ is the degree of the numerator and $m$ is the degree of the denominator.

1. If $n < m$ , then the x-axis, $y = 0$ , is the horizontal asymptote.

2. If $n = m$ , then the horizontal asymptote is the line $y = \frac{a}{b}$ .

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

Step 3

Find $n$ and $m$ .

$n = 2$

$m = 1$

Step 4

Since $n > m$ , there is no horizontal asymptote.

No Horizontal Asymptotes

Step 5

Find the oblique asymptote using polynomial division.

Set up the polynomials to be divided. If there is not a term for every exponent, insert one with a value of $0$ .

$x$

$1$

$2 x^{2}$

$4 x$

$1$

Divide the highest order term in the dividend $2 x^{2}$ by the highest order term in divisor $x$ .

					$2 x$
	$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$

Multiply the new quotient term by the divisor.

				$2 x$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			+	$2 x^{2}$	-	$2 x$

The expression needs to be subtracted from the dividend, so change all the signs in $2 x^{2} - 2 x$

				$2 x$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$

After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.

				$2 x$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$
					+	$6 x$

Pull the next terms from the original dividend down into the current dividend.

				$2 x$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$
					+	$6 x$	-	$1$

Divide the highest order term in the dividend $6 x$ by the highest order term in divisor $x$ .

				$2 x$	+	$6$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$
					+	$6 x$	-	$1$

Multiply the new quotient term by the divisor.

				$2 x$	+	$6$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$
					+	$6 x$	-	$1$
					+	$6 x$	-	$6$

The expression needs to be subtracted from the dividend, so change all the signs in $6 x - 6$

				$2 x$	+	$6$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$
					+	$6 x$	-	$1$
					-	$6 x$	+	$6$

After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.

				$2 x$	+	$6$
$x$	-	$1$		$2 x^{2}$	+	$4 x$	-	$1$
			-	$2 x^{2}$	+	$2 x$
					+	$6 x$	-	$1$
					-	$6 x$	+	$6$
							+	$5$

The final answer is the quotient plus the remainder over the divisor.

$2 x + 6 + \frac{5}{x - 1}$

The oblique asymptote is the polynomial portion of the long division result.

$y = 2 x + 6$

Step 6

This is the set of all asymptotes.

Vertical Asymptotes: $x = 1$

No Horizontal Asymptotes

Oblique Asymptotes: $y = 2 x + 6$

Step 7

Find the Asymptotes y=(2x^2+4x-1)/(x-1)

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