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Math Help - Find an expression for the cubic function...

  1. #1
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    Find an expression for the cubic function...

    Find an expression for the cubic function f if f(1) = 6 and f(-1) = f(0) = f(2) = 0.

    Answer is apparently f(x) = -3x (x+1) (x-2) but I just don't understand this problem.
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  2. #2
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    Quote Originally Posted by question111 View Post
    Find an expression for the cubic function f if f(1) = 6 and f(-1) = f(0) = f(2) = 0.

    Answer is apparently f(x) = -3x (x+1) (x-2) but I just don't understand this problem.
    You're given the roots which means that you should be able to write down the factors. Then the equation is f(x) = a(x - [-1])(x - 0)(x - 2), that is, f(x) = a(x + 1)x(x - 2).

    Now substitute f(1) = 6 and solve for a.
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