Pre-Algebra Examples

$\frac{18 x^{3} - 42 x^{2} - 78 x - 28}{6 x + 4}$

Step 1

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

$6 x$

$4$

$18 x^{3}$

$42 x^{2}$

$78 x$

$28$

Step 2

Divide the highest order term in the dividend $18 x^{3}$ by the highest order term in divisor $6 x$ .

					$3 x^{2}$
	$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$

Step 3

Multiply the new quotient term by the divisor.

				$3 x^{2}$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			+	$18 x^{3}$	+	$12 x^{2}$

Step 4

The expression needs to be subtracted from the dividend, so change all the signs in $18 x^{3} + 12 x^{2}$

				$3 x^{2}$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$

Step 5

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

				$3 x^{2}$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$

Step 6

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

				$3 x^{2}$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$

Step 7

Divide the highest order term in the dividend $- 54 x^{2}$ by the highest order term in divisor $6 x$ .

				$3 x^{2}$	-	$9 x$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$

Step 8

Multiply the new quotient term by the divisor.

				$3 x^{2}$	-	$9 x$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					-	$54 x^{2}$	-	$36 x$

Step 9

The expression needs to be subtracted from the dividend, so change all the signs in $- 54 x^{2} - 36 x$

				$3 x^{2}$	-	$9 x$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$

Step 10

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

				$3 x^{2}$	-	$9 x$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$
							-	$42 x$

Step 11

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

				$3 x^{2}$	-	$9 x$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$
							-	$42 x$	-	$28$

Step 12

Divide the highest order term in the dividend $- 42 x$ by the highest order term in divisor $6 x$ .

				$3 x^{2}$	-	$9 x$	-	$7$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$
							-	$42 x$	-	$28$

Step 13

Multiply the new quotient term by the divisor.

				$3 x^{2}$	-	$9 x$	-	$7$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$
							-	$42 x$	-	$28$
							-	$42 x$	-	$28$

Step 14

The expression needs to be subtracted from the dividend, so change all the signs in $- 42 x - 28$

				$3 x^{2}$	-	$9 x$	-	$7$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$
							-	$42 x$	-	$28$
							+	$42 x$	+	$28$

Step 15

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

				$3 x^{2}$	-	$9 x$	-	$7$
$6 x$	+	$4$		$18 x^{3}$	-	$42 x^{2}$	-	$78 x$	-	$28$
			-	$18 x^{3}$	-	$12 x^{2}$
					-	$54 x^{2}$	-	$78 x$
					+	$54 x^{2}$	+	$36 x$
							-	$42 x$	-	$28$
							+	$42 x$	+	$28$
										$0$

Step 16

Since the remander is $0$ , the final answer is the quotient.

$3 x^{2} - 9 x - 7$