Question

Y=-x^2+20x-64 what is the max height

Answer 1

36

Explanation:

The maximum height is the y-coordinate of the vertex

given a quadratic in standard form : ax² + bx + c : a ≠ 0

then the x-coordinate of the vertex is

`x_(vertex)` = -
`(b)/(2a)`

y = - x² + 20x - 64 is in standard form

with a = - 1, b = 20 and c = - 64, hence

`x_(vertex)` = -
`(20)/(-2)` = 10

substitute x = 10 into the equation for y

y = - (10)² + 20(10) - 64 = 36 ← max height