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Math Help - Concavity

  1. #1
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    Concavity

    17. For what value of x is the graph of y = 2 / (4 - x) concave downwards?

    I found the first derivative = 2/(4-x)^2

    And then the second 4/(4-x)^3

    But I think I might have messed up somewhere in there
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  2. #2
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    Quote Originally Posted by karisrou View Post
    17. For what value of x is the graph of y = 2 / (4 - x) concave downwards?

    I found the first derivative = 2/(4-x)^2

    And then the second 4/(4-x)^3

    But I think I might have messed up somewhere in there
    Concave down for values of x satisfying f''(x) < 0. In your case this happens for x > 4. (This is evident from the graph).
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