Question

The question says h= -5t^2-25t models a football being kicked in to the air. And asks for the roots. I found that the roots are -5 and 0. But the answer is 5 and 0. I know time can't be negative. But u can't just switch -5 to 5. Can you.?

Answer 1

You are correct. The function should be

h(t) = 25t - 5t^2

The -5t^2 term is due to the downward pull of gravity. The +25t indicates an initial upward velocity.

Answer 2

Parabola - 5 t ^ 2 - 25 t is concave downward.

That's why you get negative time.

You can switch - 5 to 5.

If you want to see graph go on:

w o l f r a m a l p h a . c o m

When page be open in rectangle type:

- 5 t ^ 2 - 25 t , t = 0 to - 5

and click option: =

You wil see graph