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Math Help - Cubic Functions

  1. #1
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    Cubic Functions

    A cubic function f is defined for x ∈ R as f (x) = x3+ (1 - k2​)x + k, where k is a constant. Show that -k is a root of f.

    How would I go about doing this? Help appreciated!
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  2. #2
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    Re: Cubic Functions

    Quote Originally Posted by HelenMc9 View Post
    A cubic function f is defined for x ∈ R as f (x) = x3+ (1 - k2​)x + k, where k is a constant. Show that -k is a root of f.

    How would I go about doing this? Help appreciated!
    What is f(-k)=~?
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  3. #3
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    Re: Cubic Functions

    Aah yes it's equal to zero because -k is a root... I know what to do now! thanks!!
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  4. #4
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    Re: Cubic Functions

    By the way, "root" is the wrong word here. You can find a "root" of an equation such as f(x)= 0, or a "zero" of a function, that being, of course, the root of the equation f(x)= 0.
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  5. #5
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    Re: Cubic Functions

    Quote Originally Posted by HallsofIvy View Post
    By the way, "root" is the wrong word here. .
    There does seem to be general agreement on that.
    See zero here and root there.
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