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    Post Cubic function

    Is any number exactly 2 less than its cube?

    This is what I did:
    x=x^3 - 2. I graphed the equation and came up with x = 1.521. Is this correct?
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    Quote Originally Posted by live_laugh_luv27 View Post
    Is any number exactly 2 less than its cube?

    This is what I did:
    x=x^3 - 2. I graphed the equation and came up with x = 1.521. Is this correct?
    Looks good to me.
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    Quote Originally Posted by live_laugh_luv27 View Post
    Is any number exactly 2 less than its cube?

    This is what I did:
    x=x^3 - 2. I graphed the equation and came up with x = 1.521. Is this correct?
    No. The number you've found is not EXACTLY 2 less than its cube.

    The question as stated requires you to establish the existence (or otherwise) of such a number, not to actually find the number. Existence is simple to prove since every cubic equation has at least one real root ....
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