You can
put this solution on YOUR website!The object will hit the ground when h=0

Start with the given equation

Plug in h=0
Let's use the quadratic formula to solve for t:
Starting with the general quadratic
the general solution using the quadratic equation is:
So lets solve

( notice

,

, and

)

Plug in a=-16, b=30, and c=7

Square 30 to get 900

Multiply

to get

Combine like terms in the radicand (everything under the square root)

Simplify the square root (note: If you need help with simplifying the square root, check out this
solver)

Multiply 2 and -16 to get -32
So now the expression breaks down into two parts

or
Now break up the fraction

or
Simplify

or
So these expressions approximate to

or
So the possible solutions are:

or
However, since a negative time doesn't make sense, our only solution is
So it takes about 2.085 seconds for the object to hit the ground.