Cheryl spent $45 for three scarves and a bracelet. She knows that the cost of the
2 answers:
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Solution: The speed of old freight train is 0.5 miles per minute and the speed of new dart express train is 1.5 miles per minute.
Explanation:
Let the speed of old freight train is x miles per minute and the speed of new dart express train is y miles per minute.
It is given that the speed of the dart express train is three times faster than the freight train. So, it can be written as,
....(1)
The trains are moving towards the opposite directions, therefore the distance between them is increased at the speed of miles per minute.
The distance between both train in 15 minutes is represented by .
According to the given information the distance between trains is 30 miles in 15 minutes.
Use equation (1) and put
Put this value in equation (1), to find the value of y.
Therefore, the The speed of old freight train is 0.5 miles per minute and the speed of new dart express train is 1.5 miles per minute.
(a) Compare your quadratic for h to the general quadratic ax² +bx +c. Perhaps you can see that ...
a = -16
b = 128
You use these numbers in the given formula to find the time when the ball is highest.
t = -b/(2a) = -128/(2(-16)) = 4 . . . . . . the time at which the ball is highest
(b) Evaluate the quadratic to find the height at t=4.
h = -16(4)² +128(4) +21
h = -256 +512 +21
h = 277
The maximum height of the ball is 277 ft.
a = -16
b = 128
You use these numbers in the given formula to find the time when the ball is highest.
t = -b/(2a) = -128/(2(-16)) = 4 . . . . . . the time at which the ball is highest
(b) Evaluate the quadratic to find the height at t=4.
h = -16(4)² +128(4) +21
h = -256 +512 +21
h = 277
The maximum height of the ball is 277 ft.