Question

x^3-3x^2-6x+8=0怎么求？

Answer 1

分解因式：
x³ - 3x² - 6x + 8
＝x³ - x² - 2x² + 2x - 8x + 8
＝(x³ - x²) - (2x² - 2x) - (8x - 8)
＝x²(x - 1) - 2x(x - 1) - 8(x - 1)
＝(x - 1) (x² - 2x - 8)
＝ (x - 1)(x + 2)(x - 4)

所以
x³ - 3x² - 6x + 8＝ (x - 1)(x + 2)(x - 4) ＝ 0
所以 x1 ＝ 1
x2 ＝ - 2
x3 ＝ 4

Answer 2

Answer 3

x^3-3x^2-6x+8=(x-1)*(x-4)*(x+2)=0
所以方程的解有3个,分别是 1, 4和-2

Answer 4

Answer 5

x³-3x²-6x+8=0
x³-x²-2x²-6x+8=0
(x²(x-1)-2(x²+3x-4)=0
x²(x-1)-2(x-1)(x+4)=0
(x-1)[x²-2(x+4)]=0
(x-1)(x²-2x-4)=0
x-1=0
x1=1
x²-2x-4=0
x²-2x+1-5=0
(x-1)²=5
x-1=±√5
x=1±√5
x2=1+√5
x3=1-√5