解:
原式
=1/2x(1-1/3)+1/2x(1/3-1/5)+1/2x(1/5-1/7)+……+1/2x(1/99-1/101) (最后不是100哦,因为都是奇数)
=1/2x(1-1/3+1/3-1/5+1/5-1/7+……+1/99-1/101)
=1/2x(1-1/101)
=1/2x100/101
=50/101
1/1*3=1/2(1/1-1/3)
1/3*5=1/2(1/3-1/5)
1/1*3+1/3*5+1/5*7+......+1/97*99
=1/2(1/1-1/3+1/3-1/5+....+1/97-1/99)
=1/2*98/99
=49/99