Question

A golf ball is hit from the top of a tee. The quadratic equation
𝑦 = −5𝑥2 + 20𝑥 + 0.05 describes its height, 𝑦, in metres as time, 𝑥, in seconds
passes. Determine how long the ball is in the air

Answer 1

Well, I would write that as
y = 0.05 + 20 t - 5 t^2
the initial height when t = 0 is y = 0.05
the initial velocity up is 20
and the acceleration down is 2 * 5 = 10
so we usually write that as
h = Hi + Vi t - (1/2) g t^2
that said returning to the problem
5 t^2 - 20 t - 0.05 = 0
what is t when h = 0 standard old quadratic
t = [ 20 +/- sqrt (400 + 1) ] / 10
looks like about 4 seconds

By the way. 0.05 meters is a very low tree !! Typo?

Answer 2

Oh, sorry, misread tree for tee :)

Answer 3

It's possible that it's a low tee used for putting, or it could be a typo as you suggested. However, either way, our calculations are correct assuming that the initial height is 0.05 meters.

Answer 4

No problem! It happens to the best of us.