Solve for x (x+1)(x-4)>0

$(x + 1) (x - 4) > 0$

Step 1

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

$x + 1 = 0$

$x - 4 = 0$

Step 2

Set $x + 1$ equal to $0$ and solve for $x$ .

Set $x + 1$ equal to $0$ .

$x + 1 = 0$

Subtract $1$ from both sides of the equation.

$x = - 1$

Step 3

Set $x - 4$ equal to $0$ and solve for $x$ .

Set $x - 4$ equal to $0$ .

$x - 4 = 0$

Add $4$ to both sides of the equation.

$x = 4$

Step 4

The final solution is all the values that make $(x + 1) (x - 4) > 0$ true.

$x = - 1, 4$

Step 5

Use each root to create test intervals.

$x < - 1$

$- 1 < x < 4$

$x > 4$

Step 6

Choose a test value from each interval and plug this value into the original inequality to determine which intervals satisfy the inequality.

Test a value on the interval $x < - 1$ to see if it makes the inequality true.

Choose a value on the interval $x < - 1$ and see if this value makes the original inequality true.

$x = - 4$

Replace $x$ with $- 4$ in the original inequality.

$((- 4) + 1) ((- 4) - 4) > 0$

The left side $24$ is greater than the right side $0$ , which means that the given statement is always true.

True

Test a value on the interval $- 1 < x < 4$ to see if it makes the inequality true.

Choose a value on the interval $- 1 < x < 4$ and see if this value makes the original inequality true.

$x = 0$

Replace $x$ with $0$ in the original inequality.

$((0) + 1) ((0) - 4) > 0$

The left side $- 4$ is not greater than the right side $0$ , which means that the given statement is false.

False

Test a value on the interval $x > 4$ to see if it makes the inequality true.

Choose a value on the interval $x > 4$ and see if this value makes the original inequality true.

$x = 6$

Replace $x$ with $6$ in the original inequality.

$((6) + 1) ((6) - 4) > 0$

The left side $14$ is greater than the right side $0$ , which means that the given statement is always true.

True

Compare the intervals to determine which ones satisfy the original inequality.

$x < - 1$ True

$- 1 < x < 4$ False

$x > 4$ True

$x < - 1$ True

$- 1 < x < 4$ False

$x > 4$ True

Step 7

The solution consists of all of the true intervals.

$x < - 1$ or $x > 4$

Step 8

The result can be shown in multiple forms.

Inequality Form:

$x < - 1 or x > 4$

Interval Notation:

$(- \infty, - 1) \cup (4, \infty)$

Step 9

Solve for x (x+1)(x-4)>0

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