What is the maximum value of the function \(f(x)=\sqrt{16-x^2}\)?

Correct answer: 4

For real values, \(16-x^2\ge 0\), and \(x^2\) is smallest when \(x=0\). Thus, \(f(0)=\sqrt{16}=4\), so the maximum value is 4. The value 16 is the maximum radicand, not the value of the function after taking the square root. Exam tip: For a square-root function, first maximize the expression inside the radical and then take its square root.