(1)bn≤0时bnbn>0时,a1=1,b1^2≤b1-b2设bnbn+1≤bn- bn^2=-(1/2-bn)^2+1/4<-(1/2-an )^2+1/4=an-an^2=1/n-1/n^2=(n-1)/n^2<1/(n+1) 即有bn+1(2)b1+b2+b3+……+b(2^n-1)<1+1/2+1/3+....+1/(2^n-1)1/2+1/3<1,1/4+/1/5+1/6+1/7<1,.....,1/2^(n-1)+1/[2^(n-1)+1]+....+1/(2^n-1)<2^(n-1)*[1/2^(n-1)]=1b1+b2+b3+……+b(2^n-1)<1*n=n
