Finite Math Examples

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

Step 1

Regroup terms.

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

Step 2

Factor $x^{2}$ out of $x^{4} - x^{2}$ .

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Step 2.1

Factor $x^{2}$ out of $x^{4}$ .

$x^{2} x^{2} - x^{2} - x^{3} + 2 x + 1$

Step 2.2

Factor $x^{2}$ out of $- x^{2}$ .

$x^{2} x^{2} + x^{2} \cdot - 1 - x^{3} + 2 x + 1$

Step 2.3

Factor $x^{2}$ out of $x^{2} x^{2} + x^{2} \cdot - 1$ .

$x^{2} (x^{2} - 1) - x^{3} + 2 x + 1$

Step 3

Rewrite $1$ as $1^{2}$ .

$x^{2} (x^{2} - 1^{2}) - x^{3} + 2 x + 1$

Step 4

Factor.

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Step 4.1

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - i^{2} = (a + i) (a - i)$ where $a = x$ and $i = 1$ .

$x^{2} ((x + 1) (x - 1)) - x^{3} + 2 x + 1$

Step 4.2

Remove unnecessary parentheses.

$x^{2} (x + 1) (x - 1) - x^{3} + 2 x + 1$

Step 5

Factor $- x^{3} + 2 x + 1$ using the rational roots test.

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Step 5.1

If a polynomial function has integer coefficients, then every rational zero will have the form $\frac{p}{q}$ where $p$ is a factor of the constant and $q$ is a factor of the leading coefficient.

$p = \pm 1$

$q = \pm 1$

Step 5.2

Find every combination of $\pm \frac{p}{q}$ . These are the possible roots of the polynomial function.

$\pm 1$

Step 5.3

Substitute $- 1$ and simplify the expression. In this case, the expression is equal to $0$ so $- 1$ is a root of the polynomial.

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Step 5.3.1

Substitute $- 1$ into the polynomial.

$- {(- 1)}^{3} + 2 \cdot - 1 + 1$

Step 5.3.2

Raise $- 1$ to the power of $3$ .

$- - 1 + 2 \cdot - 1 + 1$

Step 5.3.3

Multiply $- 1$ by $- 1$ .

$1 + 2 \cdot - 1 + 1$

Step 5.3.4

Multiply $2$ by $- 1$ .

$1 - 2 + 1$

Step 5.3.5

Subtract $2$ from $1$ .

$- 1 + 1$

Step 5.3.6

Add $- 1$ and $1$ .

$0$

Step 5.4

Since $- 1$ is a known root, divide the polynomial by $x + 1$ to find the quotient polynomial. This polynomial can then be used to find the remaining roots.

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

Step 5.5

Divide $- x^{3} + 2 x + 1$ by $x + 1$ .

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Step 5.5.1

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

$x$

$1$

$x^{3}$

$0 x^{2}$

$2 x$

$1$

Step 5.5.2

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

				-	$x^{2}$
	$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$

Step 5.5.3

Multiply the new quotient term by the divisor.

			-	$x^{2}$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			-	$x^{3}$	-	$x^{2}$

Step 5.5.4

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

			-	$x^{2}$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$

Step 5.5.5

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

			-	$x^{2}$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$

Step 5.5.6

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

			-	$x^{2}$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$

Step 5.5.7

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

			-	$x^{2}$	+	$x$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$

Step 5.5.8

Multiply the new quotient term by the divisor.

			-	$x^{2}$	+	$x$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					+	$x^{2}$	+	$x$

Step 5.5.9

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

			-	$x^{2}$	+	$x$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$

Step 5.5.10

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

			-	$x^{2}$	+	$x$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$
							+	$x$

Step 5.5.11

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

			-	$x^{2}$	+	$x$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$
							+	$x$	+	$1$

Step 5.5.12

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

			-	$x^{2}$	+	$x$	+	$1$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$
							+	$x$	+	$1$

Step 5.5.13

Multiply the new quotient term by the divisor.

			-	$x^{2}$	+	$x$	+	$1$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$
							+	$x$	+	$1$
							+	$x$	+	$1$

Step 5.5.14

The expression needs to be subtracted from the dividend, so change all the signs in $x + 1$

			-	$x^{2}$	+	$x$	+	$1$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$
							+	$x$	+	$1$
							-	$x$	-	$1$

Step 5.5.15

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

			-	$x^{2}$	+	$x$	+	$1$
$x$	+	$1$	-	$x^{3}$	+	$0 x^{2}$	+	$2 x$	+	$1$
			+	$x^{3}$	+	$x^{2}$
					+	$x^{2}$	+	$2 x$
					-	$x^{2}$	-	$x$
							+	$x$	+	$1$
							-	$x$	-	$1$
										$0$

Step 5.5.16

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

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

Step 5.6

Write $- x^{3} + 2 x + 1$ as a set of factors.

$x^{2} (x + 1) (x - 1) + (x + 1) (- x^{2} + x + 1)$

Step 6

Factor $x + 1$ out of $x^{2} (x + 1) (x - 1) + (x + 1) (- x^{2} + x + 1)$ .

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Step 6.1

Factor $x + 1$ out of $x^{2} (x + 1) (x - 1)$ .

$(x + 1) (x^{2} (x - 1)) + (x + 1) (- x^{2} + x + 1)$

Step 6.2

Factor $x + 1$ out of $(x + 1) (x^{2} (x - 1)) + (x + 1) (- x^{2} + x + 1)$ .

$(x + 1) (x^{2} (x - 1) - x^{2} + x + 1)$

Step 7

Apply the distributive property.

$(x + 1) (x^{2} x + x^{2} \cdot - 1 - x^{2} + x + 1)$

Step 8

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 8.1

Multiply $x^{2}$ by $x$ .

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Step 8.1.1

Raise $x$ to the power of $1$ .

$(x + 1) (x^{2} x^{1} + x^{2} \cdot - 1 - x^{2} + x + 1)$

Step 8.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$(x + 1) (x^{2 + 1} + x^{2} \cdot - 1 - x^{2} + x + 1)$

Step 8.2

Add $2$ and $1$ .

$(x + 1) (x^{3} + x^{2} \cdot - 1 - x^{2} + x + 1)$

Step 9

Move $- 1$ to the left of $x^{2}$ .

$(x + 1) (x^{3} - 1 x^{2} - x^{2} + x + 1)$

Step 10

Rewrite $- 1 x^{2}$ as $- x^{2}$ .

$(x + 1) (x^{3} - x^{2} - x^{2} + x + 1)$

Step 11

Subtract $x^{2}$ from $- x^{2}$ .

$(x + 1) (x^{3} - 2 x^{2} + x + 1)$