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Math Help - finding 2 zeros in an interval

  1. #1
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    finding 2 zeros in an interval

    Hi

    The question reads :show that the function f(x) =-x^5+4x^4-16x^3+12x+5 has two zeros in the interval (-2,0)"

    With the intermediate theory I know that f(-2) is -59 and f(0) is 5 so we know there is one zero

    But how on earth do you figure out if there is two????

    Thanks in advance
    from this Calculus beginner
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by calcbeg View Post
    Hi

    The question reads :show that the function f(x) =-x^5+4x^4-16x^3+12x+5 has two zeros in the interval (-2,0)"

    With the intermediate theory I know that f(-2) is -59 and f(0) is 5 so we know there is one zero

    But how on earth do you figure out if there is two????

    Thanks in advance
    from this Calculus beginner
    are you sure you have the right function? this has only one real zero.

    when you have the right function, you would show it has another zero the same way. find another point in (-2,0) in which the function changes sign. then you can apply the intermediate value theorem again to show there's another zero.
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  3. #3
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    Here is the function.
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