00:01
In this question we are given that the height of an object tossed upward with an initial velocity of 120 feet per second is given by the formula h equals negative 16 t squared plus 120 t we're told h is the height in fit and t is the time in seconds.
00:21
We are finding the time required for an object to return to its point of departure.
00:29
So let's assume this object is going to be tossed upward and when it's tossed upward it will start moving downward and we want to know how long does it take for it's to get back to the point where it was a point where it was it was thrown or tossed so this is simply a graph of time and displacement which you can call the height.
01:23
If we take any value of h, let's say we take conveniently the value of h as 0, that it was tossed from the reference point 0 then this equation will be 0 equals negative 16 t squared plus 120 then we need to add 16 t squared to both sides so that we have 16 t squared 16 t squared equals 120t.
02:06
Alternatively, and also we can actually just subtract 120 from both sides so that we have 100, sorry, 16 t squared minus 120 t equals 0.
02:17
So we're solving this quadratic equation by first factoring, by using factorization.
02:24
So what's a common factor? we have 4t as a common factor.
02:29
So 4 t and this will be 4 t as well minus 3 30 equals 0.
02:41
Means we're going to have two values of t...