xy=2008×1/2008=1
x的2m+1次方y的2m+2次方-xy分之1
=x的2m+1次方y的2m+1次方×y-1
=(xy)的2m+1次方×y-1
=1的2m+1次方×1/2008-1
=1/2008-1
=-2007/2008