Precalculus Examples

$x^{3} - 8 x^{2} > 0$

Step 1

Convert the inequality to an equation.

$x^{3} - 8 x^{2} = 0$

Step 2

Factor $x^{2}$ out of $x^{3} - 8 x^{2}$ .

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Step 2.1

Factor $x^{2}$ out of $x^{3}$ .

$x^{2} x - 8 x^{2} = 0$

Step 2.2

Factor $x^{2}$ out of $- 8 x^{2}$ .

$x^{2} x + x^{2} \cdot - 8 = 0$

Step 2.3

Factor $x^{2}$ out of $x^{2} x + x^{2} \cdot - 8$ .

$x^{2} (x - 8) = 0$

Step 3

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

$x^{2} = 0$

$x - 8 = 0$

Step 4

Set $x^{2}$ equal to $0$ and solve for $x$ .

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Step 4.1

Set $x^{2}$ equal to $0$ .

$x^{2} = 0$

Step 4.2

Solve $x^{2} = 0$ for $x$ .

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Step 4.2.1

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$x = \pm \sqrt{0}$

Step 4.2.2

Simplify $\pm \sqrt{0}$ .

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Step 4.2.2.1

Rewrite $0$ as $0^{2}$ .

$x = \pm \sqrt{0^{2}}$

Step 4.2.2.2

Pull terms out from under the radical, assuming positive real numbers.

$x = \pm 0$

Step 4.2.2.3

Plus or minus $0$ is $0$ .

$x = 0$

Step 5

Set $x - 8$ equal to $0$ and solve for $x$ .

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Step 5.1

Set $x - 8$ equal to $0$ .

$x - 8 = 0$

Step 5.2

Add $8$ to both sides of the equation.

$x = 8$

Step 6

The final solution is all the values that make $x^{2} (x - 8) = 0$ true.

$x = 0, 8$

Step 7

The solution consists of all of the true intervals.

$x > 8$

Step 8

Convert the inequality to interval notation.

$(8, \infty)$

Step 9