Question

у = -х^2 +4х+5


срочно​

Answer 1

$y=-x^{2}+4x+5\\\\X_{v}=-\frac{4}{-2}=2\\\\Y_{v} =-2^{2} +4*2+5=-4+8+5=9\\\\\boxed{(2 \ ; \ 9)}$

Answer 2

$y = - x^{2} + 4x + 5$

Determine the coefficients of the quadratic function a and b.

$a = - 1 \\ b = 4$

Find the x-coordinate of the vertex by substituting a = -1; b = 4 into the formula x = -b / 2a.

$x = - \frac{4}{2 \times ( - 1)} = 2$

Find the y-coordinate of the vertex by calculating the function value for x = 2.

$y = - 2^{2} + 4 \times 2 + 5 = - 4 + 8 + 5 = 9$

x = 2; y = 9.

(x, y) = (2, 9)

Correct variant is D) 2, 9.