Find all the possible values of the expression `sqrt(x^2-4)`.

Explanation

To find all the possible values of the expression \( \sqrt{x^2 - 4} \), we will follow these steps:

### Step 1: Determine the domain of the expression
The expression \( \sqrt{x^2 - 4} \) is defined when the quantity inside the square root is non-negative. Therefore, we need to solve the inequality:

\[ x^2 - 4 \geq 0 \]
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