Example

Finding the Zeros and Specific Heights for h(t)=16t2+64t+80h(t) = -16t^2 + 64t + 80

To analyze the height of an object thrown upward, modeled by the polynomial function h(t)=16t2+64t+80h(t) = -16t^2 + 64t + 80, we can find its zeros, the time it reaches a specific height, and its height at a specific time. First, to find the zeros which indicate when the object hits the ground, set h(t)=0h(t) = 0. Factoring the equation 16t2+64t+80=0-16t^2 + 64t + 80 = 0 gives 16(t24t5)=0-16(t^2 - 4t - 5) = 0, which factors further to 16(t5)(t+1)=0-16(t - 5)(t + 1) = 0. This yields t=5t = 5 and t=1t = -1. Since time cannot be negative, we discard t=1t = -1, concluding the object hits the ground at 5 seconds. Second, to find when the object is at a specific height of 80 feet, set h(t)=80h(t) = 80. Subtracting 80 from both sides gives 16t2+64t=0-16t^2 + 64t = 0. Factoring out the greatest common factor gives 16t(t4)=0-16t(t - 4) = 0, yielding t=0t = 0 and t=4t = 4. Thus, the object is at 80 feet at 0 and 4 seconds. Third, to find the height at a specific time, such as t=2t = 2 seconds, substitute 2 into the function. The result is h(2)=16(2)2+64(2)+80=144h(2) = -16(2)^2 + 64(2) + 80 = 144. The object is at 144 feet after 2 seconds.

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Updated 2026-04-30

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