Write as a Set of Linear Factors g(x)=x^3+8x^2+11x-20

$g (x) = x^{3} + 8 x^{2} + 11 x - 20$

Step 1

Factor $x^{3} + 8 x^{2} + 11 x - 20$ using the rational roots test.

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.

$g (x) = p = \pm 1, \pm 20, \pm 2, \pm 10, \pm 4, \pm 5$

$q = \pm 1$

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

$g (x) = \pm 1, \pm 20, \pm 2, \pm 10, \pm 4, \pm 5$

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

Substitute $1$ into the polynomial.

$g (x) = 1^{3} + 8 \cdot 1^{2} + 11 \cdot 1 - 20$

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

$g (x) = 1 + 8 \cdot 1^{2} + 11 \cdot 1 - 20$

Raise $1$ to the power of $2$ .

$g (x) = 1 + 8 \cdot 1 + 11 \cdot 1 - 20$

Multiply $8$ by $1$ .

$g (x) = 1 + 8 + 11 \cdot 1 - 20$

Add $1$ and $8$ .

$g (x) = 9 + 11 \cdot 1 - 20$

Multiply $11$ by $1$ .

$g (x) = 9 + 11 - 20$

Add $9$ and $11$ .

$g (x) = 20 - 20$

Subtract $20$ from $20$ .

$g (x) = 0$

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.

$g (x) = \frac{x^{3} + 8 x^{2} + 11 x - 20}{x - 1}$

Divide $x^{3} + 8 x^{2} + 11 x - 20$ by $x - 1$ .

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

$g (x) =$

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

$g (x) =$

Multiply the new quotient term by the divisor.

$g (x) =$

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

$g (x) =$

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

$g (x) =$

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

$g (x) =$

Divide the highest order term in the dividend $9 x^{2}$ by the highest order term in divisor $x$ .

$g (x) =$

Multiply the new quotient term by the divisor.

$g (x) =$

The expression needs to be subtracted from the dividend, so change all the signs in $9 x^{2} - 9 x$

$g (x) =$

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

$g (x) =$

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

$g (x) =$

Divide the highest order term in the dividend $20 x$ by the highest order term in divisor $x$ .

$g (x) =$

Multiply the new quotient term by the divisor.

$g (x) =$

The expression needs to be subtracted from the dividend, so change all the signs in $20 x - 20$

$g (x) =$

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

$g (x) =$

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

$g (x) = x^{2} + 9 x + 20$

Write $x^{3} + 8 x^{2} + 11 x - 20$ as a set of factors.

$g (x) = (x - 1) (x^{2} + 9 x + 20)$

Step 2

Factor $x^{2} + 9 x + 20$ using the AC method.

Consider the form $x^{2} + i x + c$ . Find a pair of integers whose product is $c$ and whose sum is $i$ . In this case, whose product is $20$ and whose sum is $9$ .

$g (x) = 4, 5$

Write the factored form using these integers.

$g (x) = (x - 1) ((x + 4) (x + 5))$

Remove unnecessary parentheses.

$g (x) = (x - 1) (x + 4) (x + 5)$

Write as a Set of Linear Factors g(x)=x^3+8x^2+11x-20

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