Question

初升高数学解方程题解方程2(x2次+（l/x2次）)-3(x+（l/x）)-l=0

Answer 1

2(x2次+（l/x2次）)-3(x+（l/x）)-l=0

2((x+1/x)²-2)-3(x+1/x)-1=0

2(x+1/x)²-3(x+1/x)-5=0

设x+1/x=y

则

2y²-3y-5=0

(y+1)(2y-5)=0

解得y=-1或y=5/2

则

x+1/x=-1

即x²+x+1=0,无解

或x+1/x=5/2

即2x²-5x+2=0

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

解得x=1/2或x=2

综上可得方程解为x=1/2或x=2