Originally Posted by

**ZzTop0503** Okay so here is the original equation:

A rocket is launched into the air from the top of a building. It's height (in meters) is given by:

h(t)= -5t² + 30t + 100, where t = time in seconds.

When does the rocket smash into the ground?

So, this is where I set the equation equal to zero.

0 = -5t² + 30t + 100

and since it couldn't be factored, I decided I needed to use the quadratic formula.

However, am I able to factor out the -5?

Then I got:

-5(t²-6t-20)

So, when I plugged the items in the parenthesis into the quadratic formula, I eventually got: (3 +/- √29)

Now, what I'm wondering is:

First of all, did I do everything correctly?

If so, what do I then do with the -5 I factored out in the beginning?

Any help would be appreciated, thank you for your time!