bài toán lớp 5 mà quên cách giải.

T

truonghandan0210

Đề sai hả bạn?
Dạng này ko có quy luật sao tính dc?
---------------------------------------------->?
 
D

doreamonhihi

Bài này hình như có vấn đề thật. Hình như sai ở phần khoảng cách. Phân số thứ nhất có khoảng cách là 3 đơn vị ở phần mẫu số trong phép tính, phân số thứ hai có khoảng cách là 4 đơn vị ở phần mẫu số trong phép tính và cuối cùng thì lại có khoảng cách 3 đơn vị.
 
M

minhtuan250802

tinh nhanh
1/2+3 -1/3+4-1/4+5-.....1/99+100
llllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllooooooooôoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
 
M

minhtuan250802

A=1/4 + 1/(4x7) + 1/(7x11)+ 1/(11x14) +....+ 1/(28x31).
=1/4+1/4-1/7+1/7-1/11+1/11-1/14+.....+1/28-1/31
sau đó ta bỏ các phân số giông nhau
=1/31
 
M

minhtuan250802

A=1/4 + 1/(4x7) + 1/(7x11)+ 1/(11x14) +....+ 1/(28x31).
=1/4+1/4-1/7+1/7-1/11+1/11-1/14+.....+1/28-1/31
sau đó ta bỏ các phân số giông nhau
=1/31
 
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