数学证明题(急!)X立方-3X-2=0怎么变成(X+1)(X平方-X-2)=0设x^3+x^-3=2,求x+x^-1的值设x+x^-1=t,则t^3=x^3+1/x^3+3x·x^-1(x+1/x)=2+3t→(t+1)(t^2-t-2)=0
2019-05-27
数学证明题(急!)
X立方-3X-2=0怎么变成(X+1)(X平方-X-2)=0
设x^3+x^-3=2,求x+x^-1的值
设x+x^-1=t,则t^3=x^3+1/x^3+3x·x^-1(x+1/x)
=2+3t
→(t+1)(t^2-t-2)=0
优质解答
x^3-3x-2=2
x^3+x^2-x^2-3x-2=0
x^2(x+1)-(x+1)(x+2)=0
(x+1)(x^2-x-2)=0
x^3-3x-2=2
x^3+x^2-x^2-3x-2=0
x^2(x+1)-(x+1)(x+2)=0
(x+1)(x^2-x-2)=0