设y=2007 则y-1=2006y+1=2008
则x/(y-1)+x/(y+1)=6+2/(y-1)-2/y-2/(y+1)
x*[2y/(y-1)(y+1)]=2(3+1/(y-1)-1/y-1/(y+1)]
yx=3(y²-1)+y+1-(y²-1)/y-(y-1)
yx=3y²-3+y+1-y+1/y-y+1
yx=3y²-y-1+1/y
所以x=3y-1-1/y+1/y²
即x=3*2007-1-1/2007+1/2007²
x=6020-1/2007+1/2007²