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[ 1/1 Equation]
    Work: Find the solution of equation x^3-9x^2-9x+81 = 0 .
    Question type: Equation
    Solution:
    After the equation is converted into a general formula, it is converted into:
    ( x + 3 )( x - 3 )( x - 9 )=0
    From
        x + 3 = 0
        x - 3 = 0
        x - 9 = 0
    it is concluded that:：
        x₁=-3
        x₂=3
        x₃=9    
    There are 3 solution(s).

解程的详细方法请参阅：《方程的解法》

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