Answer:
a) 72.25sec
b) 6.25secs
c) after 10.5secs and 2 secs
Step-by-step explanation:
Given the height reached by the rocket expressed as;
s(t)= -4t^2 + 50t - 84
At maximum height, the velocity of the rocket is zero i.e ds/dt = 0
ds/dt = -8t + 50
0 = -8t + 50
8t = 50
t = 50/8
t = 6.25secs
Hence it will reach the maximum height after 6.25secs
To get the maximum height, you will substitute t - 6.25s into the given expression
s(t)= -4t^2 + 50t - 84
s(6.25) = -4(6.25)^2 + 50(6.25) - 84
s(6.25) = -156.25 + 312.5 - 84
s(6.25) = 72.25feet
Hence the maximum height reached by the rocket is 72.25feet
The rocket will reach the ground when s(t) = 0
Substitute into the expression
s(t)= -4t^2 + 50t - 84
0 = -4t^2 + 50t - 84
4t^2 - 50t + 84 = 0
2t^2 - 25t + 42 = 0
2t^2 - 4t - 21t + 42 = 0
2t(t-2)-21(t-2) = 0
(2t - 21) (t - 2) = 0
2t - 21 = 0 and t - 2 = 0
2t = 21 and t = 2
t = 10.5 and 2
Hence the time the rocket will reach the ground are after 10.5secs and 2 secs
3/4
75%
0.75
75/100
theres a lot
Answer:
less
Step-by-step explanation:
5/10 is equal to one half, but 4/10 is less than one half
Answer:
The answer is 48 small shirts ordered
Step-by-step explanation:
Answer:
- Walnuts - $1.25, chocolate chips - $3.25
Step-by-step explanation:
Let walnuts = x, chocolate chips = y
<u>Set a system and solve:</u>
<u>Double the first equation and subtract the second one from it:</u>
- 6x + 10y - 6x - 2y = 40 - 14
- 8y = 26
- y = 26/8
- y = 3.25
<u>Find the value of x:</u>
- 6x + 3.25*2 = 14
- 6x = 14 - 6.5
- 6x = 7.5
- x = 7.5/6
- x = 1.25
