1/1x3+1/3x5+...1/99x101=1/2*(1-1/3)+1/2*(1/3-1/5)...+1/2*(1/99-1/101)
=1/2*(1-1/3+1/3-1/5+...+1/99-1/101)
=1/2*(1-1/101)
=50/101
1/1x3+1/3x5+...1/99x101=1/2*(1-1/3)+1/2*(1/3-1/5)...+1/2*(1/99-1/101)
=1/2*(1-1/3+1/3-1/5+...+1/99-1/101)
=1/2*(1-1/101)
=50/101