Answer: 1 second
Step-by-step explanation:
There are two ways to solve this:
1. Graph it. You will see an inverted parabola with time (in seconds) on the x axis and height (in feet) on the y axis. The top of the parabola is point (1, 36) which means at 1 second the ball will be at 36 feet. Since the balcony is at 30 feet, the ball only goes up 6 feet before it changes direction toward the ground.
2. Take the first derivative and set it equal to zero. The first derivative will give us the slope, or rate of change, of the parabola for any point t (on the x-axis). The rate of change when the ball reaches its maximum height will be zero, when it goes from a positive value (going up) to a negative value (going down).
-6t^2 + 12t + 30
First derivative = h'(t) = -12t + 12
Set h'(t) to zero: 0 = -12t + 12
t = 1 second
Either way works. Put 1 second into the original equation and it will return 36 feet. That's 36 feet aboove ground. 6 feet above the balcony from which it is thrown. You can throw better then that, I assume.
