00:01
For this problem, you are given the height of an object that was propelled from the ground to be negative 16t squared plus 80t.
00:12
All right, and that is what the blue curve is.
00:17
That's your h of t.
00:26
All right.
00:27
And then the question asks you to find the time interval, find the time interval, where the object is more than 96 feet.
00:36
So that's what this curve is y equals 96.
00:42
And this part right here is when the object would be above 96.
00:49
So our goal is to find these two points.
00:53
And to do that, we're going to set the height function equal to 96.
00:57
So we'll have negative 16 t squared plus 80t is equal to 96.
01:07
All right, then we'll have negative 16 t squared plus 80t minus 96 is equal to zero.
01:28
So anytime you're solving a quadratic equation that has the squared in it, you want zero on one side.
01:37
All right, we can factor this, so we'll take out a negative 16.
01:41
Always use a gcf.
01:42
It makes the number smaller...