Solve the Inequality for x 0<x^2-4x-5

$0 < x^{2} - 4 x - 5$

Step 1

Rewrite so $x$ is on the left side of the inequality.

$x^{2} - 4 x - 5 > 0$

Step 2

Convert the inequality to an equation.

$x^{2} - 4 x - 5 = 0$

Step 3

Factor $x^{2} - 4 x - 5$ using the AC method.

Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 5$ and whose sum is $- 4$ .

$- 5, 1$

Write the factored form using these integers.

$(x - 5) (x + 1) = 0$

Step 4

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

$x - 5 = 0$

$x + 1 = 0$

Step 5

Set $x - 5$ equal to $0$ and solve for $x$ .

Set $x - 5$ equal to $0$ .

$x - 5 = 0$

Add $5$ to both sides of the equation.

$x = 5$

Step 6

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 7

The final solution is all the values that make $(x - 5) (x + 1) = 0$ true.

$x = 5, - 1$

Step 8

Use each root to create test intervals.

$x < - 1$

$- 1 < x < 5$

$x > 5$

Step 9

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.

$0 < {(- 4)}^{2} - 4 \cdot - 4 - 5$

The left side $0$ is less than the right side $27$ , which means that the given statement is always true.

True

Test a value on the interval $- 1 < x < 5$ to see if it makes the inequality true.

Choose a value on the interval $- 1 < x < 5$ and see if this value makes the original inequality true.

$x = 0$

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

$0 < {(0)}^{2} - 4 \cdot 0 - 5$

The left side $0$ is not less than the right side $- 5$ , which means that the given statement is false.

False

Test a value on the interval $x > 5$ to see if it makes the inequality true.

Choose a value on the interval $x > 5$ and see if this value makes the original inequality true.

$x = 8$

Replace $x$ with $8$ in the original inequality.

$0 < {(8)}^{2} - 4 \cdot 8 - 5$

The left side $0$ is less than the right side $27$ , which means that the given statement is always true.

True

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

$x < - 1$ True

$- 1 < x < 5$ False

$x > 5$ True

$x < - 1$ True

$- 1 < x < 5$ False

$x > 5$ True

Step 10

The solution consists of all of the true intervals.

$x < - 1$ or $x > 5$

Step 11

The result can be shown in multiple forms.

Inequality Form:

$x < - 1 or x > 5$

Interval Notation:

$(- \infty, - 1) \cup (5, \infty)$

Step 12

Solve the Inequality for x 0<x^2-4x-5

Related Questions

Support LCMGCF.com by disabling your adblocker.