x²-3x+1=0,求2x²-5x-2+3/(x²+1)

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x²-3x+1=0,求2x²-5x-2+3/(x²+1)
x²-3x+1=0,求2x²-5x-2+3/(x²+1)

x²-3x+1=0,求2x²-5x-2+3/(x²+1)
x²-3x+1=0
x²+1=3x,
x²-3x=-1
x+1/x=3
2x²-5x-2+3/(x²+1)
=2(x²-3x)+x-2+3/(3x)
=-4+x+1/x
=-4+3=-1