Question

解方程2(x²+1/x²)-9(x+1/x)+14=0

Answer 1

2(x²+1/x²)-9(x+1/x)+14=0

2(x²+2+1/x²)-9(x+1/x)+10=0

2(x+1/x)²-9(x+1/x)+10=0

[(x+1/x)-2][2(x+1/x)-5]=0

所以x+1/x=2或x+1/x=5/2

所以x=1或x=2或x=1/2

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