Answer:
125feet
Step-by-step explanation:
Given the equation that modeled the height expressed as h = -16t^2 + 80t + 25, where h is the height and t is the time in seconds.
The arrow reaches the maximum height at dh/dt = 0
dh/dt = -32t + 80
0= -32t+80
32t = 80
t = 80/32
t = 2.5secs
substitute t = 2.5 into the formula;
h = -16t^2 + 80t + 25
h = -16(2.5)^2 + 80(2.5) + 25
h = -16(6.25)+225
h = -100+225
h = 125
Hence the maximum height the arrow reaches is 125feet
Answer:
289
Step-by-step explanation:
Hope this helps
8x + 7y = 39
4x - 14y = -68
(multiply each term in second equation by -2)
8x + 7y = 39
-8x + 28y = 136
(add both equations)
35y = 175
(divide both sides by 35)
y = 5
(substitute value of y in one of the equations)
8x + 7(5) = 39
8x + 35 = 39
8x = 4
x = 1/2
(x, y) = (1/2, 5)
Answer:
1 
Step-by-step explanation:
There are a total of 2 friends, if they have 3 cereal bars and want to split it equally then we simply need to divide the number of cereal bars by the number of friends which would give us the number of cereal bars that each individual will get, which will be represented by x
x = 3 / 2
x = 1
Finally, we can see that each friend will get a total of 1 and a half of a cereal bar.
Answer: the speed of the boat on the lake is 9 mph
Step-by-step explanation:
Let x represent the speed of the boat on the lake or in still water.
The speed of the current in a river is 6 mph. This means that if the boat goes upstream against the speed of the current, its total speed would be (x - 6)mph. If the boat goes downstream against the speed of the current, its total speed would be (x + 6)mph.
Time = distance/ speed
Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to make this trip in a total of 9 hours. This means that the time taken to travel upstream is
22.5/(x - 6). The time taken to travel downstream is
22.5/(x + 6)
Since the total time is 9 hours, it means that
22.5/(x - 6) = 22.5/(x + 6)
Cross multiplying, it becomes
22.5(x + 6) + 22.5(x - 6) = 9
Multiplying through by (x + 6)(x - 6), it becomes
22.5(x - 6) + 22.5(x + 6) = 9[(x + 6)(x - 6)]
22.5x - 135 + 22.5x + 135 = 9(x² - 6x + 6x - 36)
22.5x + 22.5x = 9x² - 324
9x² - 45x - 324 = 0
Dividing through by 9, it becomes
x² - 5x - 36 = 0
x² + 4x - 9x - 36 = 0
x(x + 4) - 9(x + 4) = 0
x - 9 = 0 or x + 4 = 0
x = 9 or x = - 4
Since the speed cannot be negative, then x = 9
