What is the function with the height in feet from the ground as the independent variable?
let f(x) = h
h = −16x^2 + 32
h − 32 = −16x^2 divide by −16
[ h − 32] / − 16 = x^2
[32 − h ] / 16 = x^2 take the positive root of both sides
√[32 − h ] / 4 = x
After about how many seconds were the keys 4 feet above the ground ?
√[32 − 4 ] / 4 = √[28 ] / 4 = √[7 ] / 2 sec ≈ 1.32 sec
