1⼀1*3+1⼀3*5+1⼀5*7+......+1⼀99*100=???

1/1*3+1/3*5+1/5*7+......+1/99*100???
2024-10-28 01:30:14
推荐回答(2个)
回答(1):

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  

回答(2):

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