Finite Math Examples

$x^{3} - 10 x^{2} + 44 x - 69$

Step 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.

$p = \pm 1, \pm 3, \pm 23, \pm 69$

$q = \pm 1$

Step 2

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

$\pm 1, \pm 3, \pm 23, \pm 69$

Step 3

Substitute the possible roots one by one into the polynomial to find the actual roots. Simplify to check if the value is $0$ , which means it is a root.

${(3)}^{3} - 10 {(3)}^{2} + 44 (3) - 69$

Step 4

Simplify the expression. In this case, the expression is equal to $0$ so $x = 3$ is a root of the polynomial.

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Step 4.1

Simplify each term.

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Step 4.1.1

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

$27 - 10 {(3)}^{2} + 44 (3) - 69$

Step 4.1.2

Raise $3$ to the power of $2$ .

$27 - 10 \cdot 9 + 44 (3) - 69$

Step 4.1.3

Multiply $- 10$ by $9$ .

$27 - 90 + 44 (3) - 69$

Step 4.1.4

Multiply $44$ by $3$ .

$27 - 90 + 132 - 69$

Step 4.2

Simplify by adding and subtracting.

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Step 4.2.1

Subtract $90$ from $27$ .

$- 63 + 132 - 69$

Step 4.2.2

Add $- 63$ and $132$ .

$69 - 69$

Step 4.2.3

Subtract $69$ from $69$ .

$0$

Step 5

Since $3$ is a known root, divide the polynomial by $x - 3$ to find the quotient polynomial. This polynomial can then be used to find the remaining roots.

$\frac{x^{3} - 10 x^{2} + 44 x - 69}{x - 3}$

Step 6

Next, find the roots of the remaining polynomial. The order of the polynomial has been reduced by $1$ .

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Step 6.1

Place the numbers representing the divisor and the dividend into a division-like configuration.

$3$	$1$	$- 10$	$44$	$- 69$

Step 6.2

The first number in the dividend $(1)$ is put into the first position of the result area (below the horizontal line).

$3$	$1$	$- 10$	$44$	$- 69$

	$1$

Step 6.3

Multiply the newest entry in the result $(1)$ by the divisor $(3)$ and place the result of $(3)$ under the next term in the dividend $(- 10)$ .

$3$	$1$	$- 10$	$44$	$- 69$
		$3$
	$1$

Step 6.4

Add the product of the multiplication and the number from the dividend and put the result in the next position on the result line.

$3$	$1$	$- 10$	$44$	$- 69$
		$3$
	$1$	$- 7$

Step 6.5

Multiply the newest entry in the result $(- 7)$ by the divisor $(3)$ and place the result of $(- 21)$ under the next term in the dividend $(44)$ .

$3$	$1$	$- 10$	$44$	$- 69$
		$3$	$- 21$
	$1$	$- 7$

Step 6.6

Add the product of the multiplication and the number from the dividend and put the result in the next position on the result line.

$3$	$1$	$- 10$	$44$	$- 69$
		$3$	$- 21$
	$1$	$- 7$	$23$

Step 6.7

Multiply the newest entry in the result $(23)$ by the divisor $(3)$ and place the result of $(69)$ under the next term in the dividend $(- 69)$ .

$3$	$1$	$- 10$	$44$	$- 69$
		$3$	$- 21$	$69$
	$1$	$- 7$	$23$

Step 6.8

Add the product of the multiplication and the number from the dividend and put the result in the next position on the result line.

$3$	$1$	$- 10$	$44$	$- 69$
		$3$	$- 21$	$69$
	$1$	$- 7$	$23$	$0$

Step 6.9

All numbers except the last become the coefficients of the quotient polynomial. The last value in the result line is the remainder.

$1 x^{2} + - 7 x + 23$

Step 6.10

Simplify the quotient polynomial.

$x^{2} - 7 x + 23$

Step 7

Solve the equation to find any remaining roots.

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Step 7.1

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 7.2

Substitute the values $a = 1$ , $b = - 7$ , and $c = 23$ into the quadratic formula and solve for $x$ .

$\frac{7 \pm \sqrt{{(- 7)}^{2} - 4 \cdot (1 \cdot 23)}}{2 \cdot 1}$

Step 7.3

Simplify.

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Step 7.3.1

Simplify the numerator.

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Step 7.3.1.1

Raise $- 7$ to the power of $2$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 1 \cdot 23}}{2 \cdot 1}$

Step 7.3.1.2

Multiply $- 4 \cdot 1 \cdot 23$ .

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Step 7.3.1.2.1

Multiply $- 4$ by $1$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 23}}{2 \cdot 1}$

Step 7.3.1.2.2

Multiply $- 4$ by $23$ .

$x = \frac{7 \pm \sqrt{49 - 92}}{2 \cdot 1}$

Step 7.3.1.3

Subtract $92$ from $49$ .

$x = \frac{7 \pm \sqrt{- 43}}{2 \cdot 1}$

Step 7.3.1.4

Rewrite $- 43$ as $- 1 (43)$ .

$x = \frac{7 \pm \sqrt{- 1 \cdot 43}}{2 \cdot 1}$

Step 7.3.1.5

Rewrite $\sqrt{- 1 (43)}$ as $\sqrt{- 1} \cdot \sqrt{43}$ .

$x = \frac{7 \pm \sqrt{- 1} \cdot \sqrt{43}}{2 \cdot 1}$

Step 7.3.1.6

Rewrite $\sqrt{- 1}$ as $i$ .

$x = \frac{7 \pm i \sqrt{43}}{2 \cdot 1}$

Step 7.3.2

Multiply $2$ by $1$ .

$x = \frac{7 \pm i \sqrt{43}}{2}$

Step 7.4

Simplify the expression to solve for the $+$ portion of the $\pm$ .

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Step 7.4.1

Simplify the numerator.

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Step 7.4.1.1

Raise $- 7$ to the power of $2$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 1 \cdot 23}}{2 \cdot 1}$

Step 7.4.1.2

Multiply $- 4 \cdot 1 \cdot 23$ .

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Step 7.4.1.2.1

Multiply $- 4$ by $1$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 23}}{2 \cdot 1}$

Step 7.4.1.2.2

Multiply $- 4$ by $23$ .

$x = \frac{7 \pm \sqrt{49 - 92}}{2 \cdot 1}$

Step 7.4.1.3

Subtract $92$ from $49$ .

$x = \frac{7 \pm \sqrt{- 43}}{2 \cdot 1}$

Step 7.4.1.4

Rewrite $- 43$ as $- 1 (43)$ .

$x = \frac{7 \pm \sqrt{- 1 \cdot 43}}{2 \cdot 1}$

Step 7.4.1.5

Rewrite $\sqrt{- 1 (43)}$ as $\sqrt{- 1} \cdot \sqrt{43}$ .

$x = \frac{7 \pm \sqrt{- 1} \cdot \sqrt{43}}{2 \cdot 1}$

Step 7.4.1.6

Rewrite $\sqrt{- 1}$ as $i$ .

$x = \frac{7 \pm i \sqrt{43}}{2 \cdot 1}$

Step 7.4.2

Multiply $2$ by $1$ .

$x = \frac{7 \pm i \sqrt{43}}{2}$

Step 7.4.3

Change the $\pm$ to $+$ .

$x = \frac{7 + i \sqrt{43}}{2}$

Step 7.5

Simplify the expression to solve for the $-$ portion of the $\pm$ .

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Step 7.5.1

Simplify the numerator.

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Step 7.5.1.1

Raise $- 7$ to the power of $2$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 1 \cdot 23}}{2 \cdot 1}$

Step 7.5.1.2

Multiply $- 4 \cdot 1 \cdot 23$ .

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Step 7.5.1.2.1

Multiply $- 4$ by $1$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 23}}{2 \cdot 1}$

Step 7.5.1.2.2

Multiply $- 4$ by $23$ .

$x = \frac{7 \pm \sqrt{49 - 92}}{2 \cdot 1}$

Step 7.5.1.3

Subtract $92$ from $49$ .

$x = \frac{7 \pm \sqrt{- 43}}{2 \cdot 1}$

Step 7.5.1.4

Rewrite $- 43$ as $- 1 (43)$ .

$x = \frac{7 \pm \sqrt{- 1 \cdot 43}}{2 \cdot 1}$

Step 7.5.1.5

Rewrite $\sqrt{- 1 (43)}$ as $\sqrt{- 1} \cdot \sqrt{43}$ .

$x = \frac{7 \pm \sqrt{- 1} \cdot \sqrt{43}}{2 \cdot 1}$

Step 7.5.1.6

Rewrite $\sqrt{- 1}$ as $i$ .

$x = \frac{7 \pm i \sqrt{43}}{2 \cdot 1}$

Step 7.5.2

Multiply $2$ by $1$ .

$x = \frac{7 \pm i \sqrt{43}}{2}$

Step 7.5.3

Change the $\pm$ to $-$ .

$x = \frac{7 - i \sqrt{43}}{2}$

Step 7.6

The final answer is the combination of both solutions.

$x = \frac{7 + i \sqrt{43}}{2}, \frac{7 - i \sqrt{43}}{2}$

Step 8

The polynomial can be written as a set of linear factors.

$(x - 3) (x - \frac{7 + i \sqrt{43}}{2}) (x - \frac{7 - i \sqrt{43}}{2})$

Step 9

These are the roots (zeros) of the polynomial $x^{3} - 10 x^{2} + 44 x - 69$ .

$x = 3, \frac{7 + i \sqrt{43}}{2}, \frac{7 - i \sqrt{43}}{2}$

Step 10