X乘X减X减1等于0,x为何值?

题目

X乘X减X减1等于0,x为何值?

答案

x*x-x-1=0.
即,x^2-x-1=0
(x-1/2)^2-1/4-1=0.
(x-1/2)^2=5/4.
(x-1)=±√5/2.
x1=1+√5/2
x2=1-√5/2.