解一个方程。

你的方程有歧义，不知道x是否在根号下，上边有人解了x不在根号下得情形，我就给出在根号下得情形吧;
即 2*x^2-2*根号(6x)=-2
这个方程两个实根和两个虚根：
x1=((18*(6*537^(1/2) + 162)^(1/2) - 9*(537^(1/2)/9 + 3)^(2/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2) - 12*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2))^(1/2) + (9*(537^(1/2)/9 + 3)^(2/3) + 12)^(3/4))^2/(36*(537^(1/2)/9 + 3)^(1/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2)),
x2=((18*(6*537^(1/2) + 162)^(1/2) - 9*(537^(1/2)/9 + 3)^(2/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2) - 12*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2))^(1/2) - (9*(537^(1/2)/9 + 3)^(2/3) + 12)^(3/4))^2/(36*(537^(1/2)/9 + 3)^(1/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2)),
x3=((- 9*(537^(1/2)/9 + 3)^(2/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2) - 18*(6*537^(1/2) + 162)^(1/2) - 12*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2))^(1/2) - (9*(537^(1/2)/9 + 3)^(2/3) + 12)^(3/4))^2/(36*(537^(1/2)/9 + 3)^(1/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2)),
x4=((- 9*(537^(1/2)/9 + 3)^(2/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2) - 18*(6*537^(1/2) + 162)^(1/2) - 12*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2))^(1/2) + (9*(537^(1/2)/9 + 3)^(2/3) + 12)^(3/4))^2/(36*(537^(1/2)/9 + 3)^(1/3)*(9*(537^(1/2)/9 + 3)^(2/3) + 12)^(1/2)).
保留几位小数是：
x1=1.3641626217983922750736168921441,
x2=0.17731115263579042699850598400978,
x3=- 0.77073688721709135103606143807693 - 1.8815485114919411500101694764357*i,
x4=- 0.77073688721709135103606143807693 + 1.8815485114919411500101694764357*i

很简单啊

2x²-2√6x+2=0
b²-4ac=24-4*2*2=8
x=（2√6±√8）/4
x=2（√6±√2）/4
x=（√6±√2）/2
x1=（√6-√2）/2，x2=（√6+√2）/2