lab-2l+(b-1)^2=0lab-2l>=0且(b-1)^2>=0所以ab-2=0且b-1=0即a=2,b=1又有1/n*(n+1)=1/n-1/(n+1)所以1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+...1/(a+99)(b+99)=1/2+1/2*3+1/3*4+……+1/100*101=1-1/2+1/2-1/3+1/3-1/4+……+1...