f(x) = -x^2 + 4x + 1
To rewrite in vertex form, complete the square:
f(x) = -(x^2 - 4x) + 1
f(x) = -(x^2 - 4x + 4 - 4) + 1
f(x) = -(x - 2)^2 + 3
Therefore, the vertex form is y = -(x - 2)^2 + 3. The vertex is at (2, 3), so h = 2 and k = 3.
The parabola opens downward, so it has a maximum value. The maximum value occurs at the vertex, so for x = 2. The maximum value is k = 3.