①因式分解：x的二次方+2xy+y的二次方-x-y-6

①x²+2xy+y²-x-y-6=(x+y)²-(x+y)-6=(x+y-3)(x+y+2)
②∵x²-3x-1=0,∴x²-1=3x,于是 x²+1/x²=(x-1/x)²+2=[(x²-1)/x]²+2=(3x/x)²+2=9+2=11