Answer:
The pebble will hit the ground 8.29 second after it is thrown.
Step-by-step explanation:
Given that,
The height of the pebble after t seconds is given by the equation
h= -16t²+24 t+900.
When the pebble hit the ground, the height of the pebble will be zero.
So putting h=0 in the given equation.
0 = -16t²+24 t+900
⇒-4(4t²-6t-225)=0
⇒4t²-6t-225=0
Applying quadratic formula
, here a=4, b= -6 and c= -225.

⇒ t = 8.29, -6.79
Since time can not negative.
∴t=8.29 seconds.
The pebble will hit the ground 8.29 second after it is thrown.
Answer:
<h2>3 months</h2>
Step-by-step explanation:
Answer:
31/15 or 2 1/15
Step-by-step explanation:
The common denominator is 15. Convert both to an improper fraction and simplify.
M 1: 64
M 2: 49
M 3: 87
M 4: 44
Answer:
1.5seconds
Step-by-step explanation:
When the ball hits the ground, the height is equal to zero. So find t when H=0:
H=16t²+8t+80
0=16t²+8t+80
0=2t²+t+10
0=(2t-3)(t+2)
So (2t-3)=0, or (t+2)=0
So t=1.5 or t=-2. Time can't be negative though, so we take our answer as 1.5seconds