Algebra Examples

$x^{2} - 10 x + 9$

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.

$p = \pm 1, \pm 3, \pm 9$

$q = \pm 1$

Step 2

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

$\pm 1, \pm 3, \pm 9$

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.

${(1)}^{2} - 10 \cdot 1 + 9$

Step 4

Simplify the expression. In this case, the expression is equal to $0$ so $x = 1$ is a root of the polynomial.

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Step 4.1

Simplify each term.

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Step 4.1.1

One to any power is one.

$1 - 10 \cdot 1 + 9$

Step 4.1.2

Multiply $- 10$ by $1$ .

$1 - 10 + 9$

Step 4.2

Simplify by adding and subtracting.

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Step 4.2.1

Subtract $10$ from $1$ .

$- 9 + 9$

Step 4.2.2

Add $- 9$ and $9$ .

$0$

Step 5

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.

$\frac{x^{2} - 10 x + 9}{x - 1}$

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.

$1$	$1$	$- 10$	$9$

Step 6.2

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

$1$	$1$	$- 10$	$9$

	$1$

Step 6.3

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

$1$	$1$	$- 10$	$9$
		$1$
	$1$

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.

$1$	$1$	$- 10$	$9$
		$1$
	$1$	$- 9$

Step 6.5

Multiply the newest entry in the result $(- 9)$ by the divisor $(1)$ and place the result of $(- 9)$ under the next term in the dividend $(9)$ .

$1$	$1$	$- 10$	$9$
		$1$	$- 9$
	$1$	$- 9$

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.

$1$	$1$	$- 10$	$9$
		$1$	$- 9$
	$1$	$- 9$	$0$

Step 6.7

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

$(1) x - 9$

Step 6.8

Simplify the quotient polynomial.

$x - 9$

Step 7

Add $9$ to both sides of the equation.

$x = 9$

Step 8

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

$(x - 1) (x - 9)$

Step 9

These are the roots (zeros) of the polynomial $x^{2} - 10 x + 9$ .

$x = 1, 9$

Step 10

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