# Algebra

An object is fired vertically upward with an initial speed of 68.6 meters/second. After t seconds, the height is shown by
y = -4.9 t^2 + 68.6 t meters. Given that this object has an initial speed of 68.6 m/s, what is the maximum height it will reach? How long did it take the rocket to reach the maximum height?

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1. Using calculus, it would be finding dy/dt and equating to zero to solve for t.

Since it is algebra, you could complete squares:
y=-4.9(t-7)²+49*4.9
=-4.9(t-7)²+240.1
which means that the maximum height of 240.1 m at t=7.

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