Solve for x x^2>=81

Rewrite ${\displaystyle 81}$ as ${\displaystyle 9^2}$.

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

First, use the positive value of the ${\displaystyle \pm }$ to find the first solution.

Next, use the negative value of the ${\displaystyle \pm }$ to find the second solution. Since this is an inequality, flip the direction of the inequality sign on the ${\displaystyle -}$ portion of the solution.

The complete solution is the result of both the positive and negative portions of the solution.

${\displaystyle x\ge 9}$ or ${\displaystyle x\le -9}$