Ja'von kicks a soccer ball into the air. the function f(x) = –16(x – 2)2 + 64 represents the height of the ball, in feet, as a function of time, x, in seconds. what is the maximum height the ball reaches?
2feet
16 feet
32 feet
64 feet

Ok. So we can the maximum of a negative quadratic function by solving: ymax = c - (b^2/4a)
First we set the equation equal to 0, then multiply it out to determine the a, b, and c:
f(x) = –16(x – 2)^2 + 64
–16(x – 2)^2 + 64 = 0
-16 (x^2 - 4x + 4) + 64 = 0
-16x^2 + 64x -64 + 64 = 0
-16x^2 + 64x = 0
Now a = x^2 coefficient = -16
b = x coefficient = +64, c = 0
ymax = c - (b^2/4a)
ymax = 0 - (64^2/(4×-16)) = -(4096/-64)
= -(-256) = 256
So the maximum height is 256.
Is that not an option??