If the maximum value of the parabola y = - x2 + 4x + k is 3, then K=______ .

If the maximum value of the parabola y = - x2 + 4x + k is 3, then K=______ .

The maximum value of ∵ parabola y = - x2 + 4x + k is 3, ∵ 4K − 16 − 4 = 3, ∵ k = - 1