Algebra Examples

Use the long division method to find the result when $2 x^{3} + 15 x^{2} - 16 x + 4$ is divided by $2 x - 1$

Step 1

Write the problem as a mathematical expression.

Use the long division method to find the result when $\frac{2 x^{3} + 15 x^{2} - 16 x + 4}{2 x - 1}$

Step 2

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

$2 x$

$1$

$2 x^{3}$

$15 x^{2}$

$16 x$

$4$

Step 3

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

					$x^{2}$
	$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$

Step 4

Multiply the new quotient term by the divisor.

				$x^{2}$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			+	$2 x^{3}$	-	$x^{2}$

Step 5

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

				$x^{2}$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$

Step 6

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

				$x^{2}$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$

Step 7

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

				$x^{2}$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$

Step 8

Divide the highest order term in the dividend $16 x^{2}$ by the highest order term in divisor $2 x$ .

				$x^{2}$	+	$8 x$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$

Step 9

Multiply the new quotient term by the divisor.

				$x^{2}$	+	$8 x$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					+	$16 x^{2}$	-	$8 x$

Step 10

The expression needs to be subtracted from the dividend, so change all the signs in $16 x^{2} - 8 x$

				$x^{2}$	+	$8 x$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$

Step 11

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

				$x^{2}$	+	$8 x$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$
							-	$8 x$

Step 12

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

				$x^{2}$	+	$8 x$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$
							-	$8 x$	+	$4$

Step 13

Divide the highest order term in the dividend $- 8 x$ by the highest order term in divisor $2 x$ .

				$x^{2}$	+	$8 x$	-	$4$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$
							-	$8 x$	+	$4$

Step 14

Multiply the new quotient term by the divisor.

				$x^{2}$	+	$8 x$	-	$4$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$
							-	$8 x$	+	$4$
							-	$8 x$	+	$4$

Step 15

The expression needs to be subtracted from the dividend, so change all the signs in $- 8 x + 4$

				$x^{2}$	+	$8 x$	-	$4$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$
							-	$8 x$	+	$4$
							+	$8 x$	-	$4$

Step 16

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

				$x^{2}$	+	$8 x$	-	$4$
$2 x$	-	$1$		$2 x^{3}$	+	$15 x^{2}$	-	$16 x$	+	$4$
			-	$2 x^{3}$	+	$x^{2}$
					+	$16 x^{2}$	-	$16 x$
					-	$16 x^{2}$	+	$8 x$
							-	$8 x$	+	$4$
							+	$8 x$	-	$4$
										$0$

Step 17

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

$x^{2} + 8 x - 4$