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On line Solution of Monovariate Equation：
    Input any unary equation directly, and then click the "Next" button to obtain the solution of the equation.
    It supports equations that contain mathematical functions.
    Current location：Equations > Monovariate Equation > The history of univariate equation calculation > Answer

    Overview: 1 questions will be solved this time.Among them
           ☆1 equations

[ 1/1 Equation]
    Work: Find the solution of equation (400-40*x)*(400-40*x)+(300-20*x)(300-20*x) = 200*200 .
    Question type: Equation
    Solution:Original question:
     (400 − 40 x )(400 − 40 x ) + (300 − 20 x )(300 − 20 x ) = 200 × 200
    Remove the bracket on the left of the equation:
     Left side of the equation = 400(400 − 40 x ) − 40 x (400 − 40 x ) + (300 − 20 x )(300 − 20 x )
                                             = 400 × 400 − 400 × 40 x − 40 x (400 − 40 x ) + (300 − 20 x )(300 − 20 x )
                                             = 160000 − 16000 x − 40 x (400 − 40 x ) + (300 − 20 x )(300 − 20 x )
                                             = 160000 − 16000 x − 40 x × 400 + 40 x × 40 x + (300 − 20 x )(300 − 20 x )
                                             = 160000 − 16000 x − 16000 x + 1600 x x + (300 − 20 x )(300 − 20 x )
                                             = 160000 − 32000 x + 1600 x x + (300 − 20 x )(300 − 20 x )
                                             = 160000 − 32000 x + 1600 x x + 300(300 − 20 x ) − 20 x (300 − 20 x )
                                             = 160000 − 32000 x + 1600 x x + 300 × 300 − 300 × 20 x − 20
                                             = 160000 − 32000 x + 1600 x x + 90000 − 6000 x − 20 x (300 − 20 x )
                                             = 250000 − 38000 x + 1600 x x − 20 x (300 − 20 x )
                                             = 250000 − 38000 x + 1600 x x − 20 x × 300 + 20 x × 20
                                             = 250000 − 38000 x + 1600 x x − 6000 x + 400 x x
                                             = 250000 − 44000 x + 1600 x x + 400 x x
    The equation is transformed into :
     250000 − 44000 x + 1600 x x + 400 x x = 200 × 200
     Right side of the equation = 40000
    The equation is transformed into :
     250000 − 44000 x + 1600 x x + 400 x x = 40000

    After the equation is converted into a general formula, it is converted into:
    ( x - 7 )( x - 15 )=0
    From
        x - 7 = 0
        x - 15 = 0
    it is concluded that:：
        x1=7
        x2=15    
    There are 2 solution(s).

解一元二次方程的详细方法请参阅：《一元二次方程的解法》


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