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Math Help - word problem

  1. #1
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    word problem

    Any help would be greatly appreciated because I am totally lost.

    A flare is launched upwards at an initial velocity of 80 ft. from a height of 224 ft. Its height, in feet, h(t), after t seconds is given by: h(t)=-16t^2+80t+224
    After how long will the flare reach the ground?
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  2. #2
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    Quote Originally Posted by imbadatmath View Post
    Any help would be greatly appreciated because I am totally lost.

    A flare is launched upwards at an initial velocity of 80 ft. from a height of 224 ft. Its height, in feet, h(t), after t seconds is given by: h(t)=-16t^2+80t+224
    After how long will the flare reach the ground?

    Since we want to know when it will hit the ground we are looking for a value of t such that h(t)=0 remember h is the height of the flare.

    so we need to solve 0=-16t^2+80t+224 so if we factor we get..

    0=-16t^2+80t+224 \iff 0=-16(t^2-5t-14) \iff 0= -16(t+2)(t-7) so our two solutions are t=-2 and t=7

    We need to disreguard one solution (because it doesn't make sense in the context of the problem) t=-2 so it will take 7 seconds for the flare to hit the ground.

    Yeah
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  3. #3
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    thank you so much
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