Check the pictures below.
if we knew the roots/solutions of the equation, we can set h(s) = 0 and solve for "s" to find out how many seconds is it when the height is 0.
if you notice in the first picture, when f(x) = 0, is when the parabola hits a root/solution or the ground, for David he'll be hitting the water surface, and the equation that has both of those roots/solutions conspicuous is
h(s) = -4.9(s - 2)(s + 1).
Let be the dimensions of the rectangle. We know the equations for both area and perimeter:
So, we have the following system:
From the second equation, we can deduce
Plug this in the first equation to get
Refactor as
And solve with the usual quadratic formula to get
Both solutions are feasible, because they're both positive.
If we chose the positive solution, we have
If we choose the negative solution, we have
So, we're just swapping the role of and
. The two dimensions of the rectangle are
and