x三次方-10x²+25x-12=0

题目

x三次方-10x²+25x-12=0

答案

√x^3-10x^2+25x-12=0
用拆项法：
x^3-6x^2+9x-4x^2+16x-12=0
x(x-3)^2-4(x-1)(x-3)=0
[x(x-3)-4(x-1)](x-3)=0
(x^2-7x+4)(x-3)=0
即：
x^2-7x+4=0、x-3=0
得：
x1=(7+√33)/2
x2=(7-√33)/2
x3=3