a-2=0;a=2;
ab-2=0;
2b=2;b=1;
1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+```+1/(a+2006)(b+2006)
=1/(1×2)+1/(2×3)+1/(3×4)+...+1/(2007×2008)
=1-1/2+1/2-1/3+1/3-1/4+.+1/2007-1/2008
=1-1/2008
=2007/2008
a-2=0;a=2;
ab-2=0;
2b=2;b=1;
1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+```+1/(a+2006)(b+2006)
=1/(1×2)+1/(2×3)+1/(3×4)+...+1/(2007×2008)
=1-1/2+1/2-1/3+1/3-1/4+.+1/2007-1/2008
=1-1/2008
=2007/2008