Let $f:[2, ∞) → X$ be define by $f(x)=4x-x^2$. Then, f is invertible, if X =
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (-∞, 4]
It is evident from the graph of f(x) that it represents an arc of the parabola $y = 4x - x^2$ lying on the right side of its vertex (2, 4). Clearly, range of f = (-∞, 4]. Hence, X=(-∞, 4].
