A football is kicked up from ground level at an initial upward velocity of 80 ft./s. The equation h=-16t^2 + 80t give the height h of the football after t seconds. What are realistic values for t?

Step-by-step explanation:

Note that the given height equation, which is a quadratic) has a graph that opens downward.  Borrowing the quadratic formula, we find the roots of this equation, that is, the t values at which h(t) = 0:

The coefficients of this equation are a = -16, b = 80 and c = 0.

We need to find the roots of this quadratic.  By the quadratic formula,

      -(80) ±√(80² - 4(-16)(0) )         -80 ± 0

t = = = -5/2 and -5/2 (seconds).

                 2(-16)                               -32

The initial height is 0 at t = 0 seconds and the final height 0 at 5/2 seconds.

step-by-step explanation:

one day the were 5 ducks, and their king told them to multiply their kingdom. so each went their own seperate way and met 4 other ducks on their journey.

when the ducks returned to their kingdom, it was discovered that there were 5 groups of 5 ducks. when the kind counted the number of ducks in total (including the ones he sent out earlier) he counted 25.

therefore 5 times 5 is 25.

the end. : )