Задача по SAT. Математическая часть. h = − 4.9t^2 + 25t
The equation above expresses the approximate
height h, in meters, of a ball t seconds after it is
launched vertically upward from the ground with an
initial velocity of 25 meters per second. After
approximately how many seconds will the ball hit the
ground?
A) 3.5
B) 4.0
C) 4.5
D) 5.0

Предыдущий
вопрос Следующий
вопрос

To find out when the ball hits the ground, we need to find when the height h is equal to 0.

So, we set the equation h = 0 and solve for t:

0 = -4.9t^2 + 25t

4.9t^2 - 25t = 0
t(4.9t - 25) = 0

This equation is true when either t = 0 or 4.9t - 25 = 0.

Solving for t in the second part:
4.9t - 25 = 0
4.9t = 25
t = 25 / 4.9
t ≈ 5.1

Therefore, the ball will hit the ground after approximately 5 seconds.

The answer is D) 5.0.