SOLUTION: An object is launched from ground level directly upward at a rate of 144 feet per second. The equation for the object's height is h(x)=-16x^2+144x. What is the value of x, is the
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Question 1130551: An object is launched from ground level directly upward at a rate of 144 feet per second. The equation for the object's height is h(x)=-16x^2+144x. What is the value of x, is the object at or above a height of 288 feet? How long is the object at or above this height? Answer by ikleyn(52946) (Show Source):
-16x^2 + 144x = 288 (1) ====>
16x^2 - 144x + 288 = 0 is equivalent to
x^2 - 9x + 18 = 0
(x-3)*(x-6) = 0.
The roots of the equation (1) are 3 and 6 seconds.
So, the object is above the height of 144 ft from the time moment of 3 seconds till the time moment of 6 seconds,
or exactly 3 = 6 - 3 seconds. ANSWER
