Solve by Factoring x^3+3x^2-9x=27

$x^{3} + 3 x^{2} - 9 x = 27$

Step 1

Subtract $27$ from both sides of the equation.

$x^{3} + 3 x^{2} - 9 x - 27 = 0$

Step 2

Factor out the greatest common factor from each group.

Group the first two terms and the last two terms.

$(x^{3} + 3 x^{2}) - 9 x - 27 = 0$

Factor out the greatest common factor (GCF) from each group.

$x^{2} (x + 3) - 9 (x + 3) = 0$

Step 3

Factor the polynomial by factoring out the greatest common factor, $x + 3$ .

$(x + 3) (x^{2} - 9) = 0$

Step 4

Rewrite $9$ as $3^{2}$ .

$(x + 3) (x^{2} - 3^{2}) = 0$

Step 5

Factor.

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = x$ and $b = 3$ .

$(x + 3) ((x + 3) (x - 3)) = 0$

Remove unnecessary parentheses.

$(x + 3) (x + 3) (x - 3) = 0$

Step 6

Combine exponents.

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

${(x + 3)}^{1 + 1} (x - 3) = 0$

Add $1$ and $1$ .

${(x + 3)}^{2} (x - 3) = 0$

Step 7

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

${(x + 3)}^{2} = 0$

$x - 3 = 0$

Step 8

Set ${(x + 3)}^{2}$ equal to $0$ and solve for $x$ .

Set ${(x + 3)}^{2}$ equal to $0$ .

${(x + 3)}^{2} = 0$

Solve ${(x + 3)}^{2} = 0$ for $x$ .

Set the $x + 3$ equal to $0$ .

$x + 3 = 0$

Subtract $3$ from both sides of the equation.

$x = - 3$

Step 9

Set $x - 3$ equal to $0$ and solve for $x$ .

Set $x - 3$ equal to $0$ .

$x - 3 = 0$

Add $3$ to both sides of the equation.

$x = 3$

Step 10

The final solution is all the values that make ${(x + 3)}^{2} (x - 3) = 0$ true.

$x = - 3, 3$

Solve by Factoring x^3+3x^2-9x=27

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