Question

解方程X的三次方减去X的二次方的二倍再加一等于零

Answer 1

x^3-2x^2+1=0

(x-1)(x^2-x-1)=0

x-1=0即x=1或x^2-x-1=0

x^2-x-1=0

(x-1/2)^2=5/4

x-1/2=±√5/2

x=(1+√5)/2或x=(1-√5)/2

综上x=1或x=(1+√5)/2或x=(1-√5)/2