Precalculus Examples

$\frac{3 x^{4} - 5 x^{3} - 20 x - 5}{x^{2} + x + 3}$

Step 1

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

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

Step 2

Divide the highest order term in the dividend $3 x^{4}$ by the highest order term in divisor $x^{2}$ .

$3 x^{2}$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

Step 3

Multiply the new quotient term by the divisor.

$3 x^{2}$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

Step 4

The expression needs to be subtracted from the dividend, so change all the signs in $3 x^{4} + 3 x^{3} + 9 x^{2}$

$3 x^{2}$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

Step 5

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

						$3 x^{2}$
$x^{2}$	+	$x$	+	$3$		$3 x^{4}$	-	$5 x^{3}$	+	$0 x^{2}$	-	$20 x$	-	$5$
					-	$3 x^{4}$	-	$3 x^{3}$	-	$9 x^{2}$
							-	$8 x^{3}$	-	$9 x^{2}$

Step 6

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

						$3 x^{2}$
$x^{2}$	+	$x$	+	$3$		$3 x^{4}$	-	$5 x^{3}$	+	$0 x^{2}$	-	$20 x$	-	$5$
					-	$3 x^{4}$	-	$3 x^{3}$	-	$9 x^{2}$
							-	$8 x^{3}$	-	$9 x^{2}$	-	$20 x$

Step 7

Divide the highest order term in the dividend $- 8 x^{3}$ by the highest order term in divisor $x^{2}$ .

						$3 x^{2}$	-	$8 x$
$x^{2}$	+	$x$	+	$3$		$3 x^{4}$	-	$5 x^{3}$	+	$0 x^{2}$	-	$20 x$	-	$5$
					-	$3 x^{4}$	-	$3 x^{3}$	-	$9 x^{2}$
							-	$8 x^{3}$	-	$9 x^{2}$	-	$20 x$

Step 8

Multiply the new quotient term by the divisor.

						$3 x^{2}$	-	$8 x$
$x^{2}$	+	$x$	+	$3$		$3 x^{4}$	-	$5 x^{3}$	+	$0 x^{2}$	-	$20 x$	-	$5$
					-	$3 x^{4}$	-	$3 x^{3}$	-	$9 x^{2}$
							-	$8 x^{3}$	-	$9 x^{2}$	-	$20 x$
							-	$8 x^{3}$	-	$8 x^{2}$	-	$24 x$

Step 9

The expression needs to be subtracted from the dividend, so change all the signs in $- 8 x^{3} - 8 x^{2} - 24 x$

$3 x^{2}$

$8 x$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

$8 x^{3}$

$9 x^{2}$

$20 x$

$8 x^{3}$

$8 x^{2}$

$24 x$

Step 10

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

$3 x^{2}$

$8 x$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

$8 x^{3}$

$9 x^{2}$

$20 x$

$8 x^{3}$

$8 x^{2}$

$24 x$

$x^{2}$

$4 x$

Step 11

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

$3 x^{2}$

$8 x$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

$8 x^{3}$

$9 x^{2}$

$20 x$

$8 x^{3}$

$8 x^{2}$

$24 x$

$x^{2}$

$4 x$

$5$

Step 12

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

$3 x^{2}$

$8 x$

$1$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

$8 x^{3}$

$9 x^{2}$

$20 x$

$8 x^{3}$

$8 x^{2}$

$24 x$

$x^{2}$

$4 x$

$5$

Step 13

Multiply the new quotient term by the divisor.

						$3 x^{2}$	-	$8 x$	-	$1$
$x^{2}$	+	$x$	+	$3$		$3 x^{4}$	-	$5 x^{3}$	+	$0 x^{2}$	-	$20 x$	-	$5$
					-	$3 x^{4}$	-	$3 x^{3}$	-	$9 x^{2}$
							-	$8 x^{3}$	-	$9 x^{2}$	-	$20 x$
							+	$8 x^{3}$	+	$8 x^{2}$	+	$24 x$
									-	$x^{2}$	+	$4 x$	-	$5$
									-	$x^{2}$	-	$x$	-	$3$

Step 14

The expression needs to be subtracted from the dividend, so change all the signs in $- x^{2} - x - 3$

$3 x^{2}$

$8 x$

$1$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

$8 x^{3}$

$9 x^{2}$

$20 x$

$8 x^{3}$

$8 x^{2}$

$24 x$

$x^{2}$

$4 x$

$5$

$x^{2}$

$x$

$3$

Step 15

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

$3 x^{2}$

$8 x$

$1$

$x^{2}$

$x$

$3$

$3 x^{4}$

$5 x^{3}$

$0 x^{2}$

$20 x$

$5$

$3 x^{4}$

$3 x^{3}$

$9 x^{2}$

$8 x^{3}$

$9 x^{2}$

$20 x$

$8 x^{3}$

$8 x^{2}$

$24 x$

$x^{2}$

$4 x$

$5$

$x^{2}$

$x$

$3$

$5 x$

$2$

Step 16

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

$3 x^{2} - 8 x - 1 + \frac{5 x - 2}{x^{2} + x + 3}$