0.5(1-1/3+1/3-1/5+1/5............-1/101)=0.5(1-1/101)=50/101
0.5(1-1/3+1/3-1/5+1/5............-1/101)=0.5(1-1/101)=50/101
0.5(1-1/3+1/3-1/5+1/5............-1/101)=0.5(1-1/101)=50/101
0.5(1-1/3+1/3-1/5+1/5............-1/101)=0.5(1-1/101)=50/101
就是这样!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1/n-1/(n+2)=1/(n*(n+2))
所以题=0.5(1-1/3+1/3-1/5......+1/99-1/101)
=0.5*(1-1/101)
=50/101
0.5(1-1/3+1/3-1/5+1/5............-1/101)=0.5(1-1/101)=50/101
就是这样