Find the range of the function f(x) = sqrt(4 - x²) + sqrt(x² - 1).
[sqrt(3), sqrt(7)]
[sqrt(3), sqrt(6)]
[sqrt(2), sqrt(3)]
[sqrt(3), 3]
Correct answer: [sqrt(3), sqrt(6)]
Solution
The domain is 1 <= |x| <= 2. With t = x² in [1,4], analyse g(t) = sqrt(4-t) + sqrt(t-1). The minimum occurs at the endpoints and the maximum at the symmetric point t = 5/2.