解方程X的3次方-3X+2=0

问题描述:

解方程X的3次方-3X+2=0

x^3 - 3x + 2 =0 ==> x^^3 - x - 2x +2 =0 ==> x(x^2 - 1) - 2(x -1) = 0 ==> (x -1)[(x(x+1) - 2] = 0 ==> (x -1)(x^2 + x -2) = 0 ==> (x -1)(x-1)(x +2) = 0 ==> x = 1,-2