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Math Help - Pre-Calculus Problem

  1. #1
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    Pre-Calculus Problem

    The number D (in thousands) of earned degrees conferred annually in the U.S. from 1950 to 1995 is approximated by the model :

    D= -0.0977t^2+47.1174t+291.5651

    where t=0 represents 1950.

    Question: According to this model, estimate when the number of degrees will exceed 2,500,000.

    Thankyou!
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ss103 View Post
    The number D (in thousands) of earned degrees conferred annually in the U.S. from 1950 to 1995 is approximated by the model :

    D= -0.0977t^2+47.1174t+291.5651

    where t=0 represents 1950.

    Question: According to this model, estimate when the number of degrees will exceed 2,500,000.

    Thankyou!
    here, t gives the time in years since 1950. therefore, if we can find t when the degrees exceed 2,500,000 we can tell the year that it happens, which is the "when" we are looking for.

    so plug in D = 2,500,000 and solve the quadratic equation for t

    2500000 = -0.0977t^2 + 47.1174t + 291.5651

    => -0.0977t^2 + 47.1174t - 2499708.435 = 0


    i suggest using the quadratic formula, do you remember it?
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  3. #3
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    yes. i tried using the quadratic formula but i received a negative number under the square root sign. so the quadratic formuka didnt work. :/
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ss103 View Post
    yes. i tried using the quadratic formula but i received a negative number under the square root sign. so the quadratic formuka didnt work. :/
    yes, that is true. perhaps there is a problem with the question. check your numbers to make sure they are correct. 2,500,000 does seem strange. check your signs as well
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  5. #5
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    yeah. i checked it, it is all right. is there another way to do it instead of the quadratic formula?
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  6. #6
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ss103 View Post
    yeah. i checked it, it is all right. is there another way to do it instead of the quadratic formula?
    if the quadratic formula won't work, nothing else will. the graph does not touch the x-axis, it will have complex roots no matter what method you use
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