x²-2x-1=0x-2-1/x=0x-1/x=2(x-1/x)²=2²=4x²+1/x²-2=4x²+1/x²=6(x+1/x)²=x²+1/x²+2=6+2=8x+1/x=正负2倍根2x的四次方+1/x的四次方=(x²+1/x²)²-2=6&...