00:01
To answer this question, we can use the quadratic formula.
00:06
When will the height of the object be 65 feet? that means h is 65.
00:25
We want to set the equation equal to 0.
00:33
So subtract 65 from both sides.
00:38
Now multiply the equation by negative 1 if you want to, and we can use the quadratic formula.
00:59
Opposite of b plus or minus square root in my calculator, i will put b squared, that's 16 squared, minus 4 times b squared is negative 87 squared, minus 4 times a, which is 16, times c, which is 47, all over 2 times a.
01:33
87 plus the square root of 4561, close the parentheses, enter, divided by 32 is 4 .8 seconds.
01:55
If we were to subtract, we would get 0 .61 seconds.
02:12
So the object is at a height of 65 feet at both of these times.
02:19
That's because the object was thrown from a height of 18...