If a toy rocket is launched vertically upward from ground level with an initial velocity of 128 feet per second then its height H after T seconds is given by the equation h(t)=-16t^2+128t (if air resistance is neglected). When will the object reach its maximum height?
A. 8 seconds
B. 6 seconds
C. 0 seconds
D. 4 seconds

We have been given that a toy rocket is launched vertically upward from ground level with an initial velocity of 128 feet per second then its height H after T seconds is given by the equation (if air resistance is neglected).

We are asked to find the time when the object will reach its maximum height.

We can see our given equation is a downward opening parabola, so its maximum point will be vertex of parabola.

We know that x coordinate of vertex is .

We can see from our given equation that and .

Therefore, the object will reach its maximum height after 4 seconds and option D is the correct choice.

t = 3

step-by-step explanation:

put t = 3 in this expression :

(3²-1)(3²-2)(3² - 3)(3² - 4) = 8×7×6×5 = 56×30 = 1680

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step-by-step explanation:

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