Question

The ball's height (in meters above the ground), xxx seconds after Antoine threw it, is modeled by: h(x)=-2x^2+4x+16 How many seconds after being thrown will the ball hit the ground? seconds

Answer 1

Explanation:

If we are given the quadratic model, we know that the height of anything on the ground is 0 meters, so that model becomes

`0=-2t^2+4t+16` I changed your x's to t's since t is for time.

Now we need to factor that quadratic and solve for time:

`0=-2(t^2-2t-8)`

Since -2 definitely does not equal 0, then

`t^2-2t-8=0`

Factor that and find t values of 4 and -2. Again, we know that time will never be negative, so

t = 4 seconds.