The domain of f(x)=√4-x2 ?

The domain of f(x) = √(4 - x^2) is all real numbers between -2 and 2, inclusive. This is because the expression inside the square root, 4 - x^2, must be greater than or equal to 0 for the function to be defined. Solving the inequality 4 - x^2 ≥ 0, we get x^2 ≤ 4, which means -2 ≤ x ≤ 2.