\(A=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
\(A=\frac{5}{28}+\frac{5}{70}+\frac{5}{130}+...+\frac{5}{700}\)
\(\frac{3A}{5}=\frac{3}{4\times7}+\frac{3}{7\times10}+\frac{3}{10\times13}+...+\frac{3}{25\times28}\)
\(\frac{3A}{5}=\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{25}-\frac{1}{28}\)
\(\frac{3A}{5}=\frac{1}{4}-\frac{1}{28}\)
\(\frac{3A}{5}=\frac{3}{14}\)
\(A=\frac{3}{14}\times\frac{5}{3}\)
\(A=\frac{5}{14}\)
tính tổng M=\(\dfrac{10}{56}+\dfrac{10}{140}+\dfrac{10}{260}+....+\dfrac{260}{1400}\)
Tính tổng : 10/56 + 10/140 + 10/260...+10/1400
1, Tính tổng
A= 10/56 + 10/140 + 10/260 +....+ 10/1400
tính tổng S=10/56+10/140+10/260+..............+10/1400
Tính tổng: M=10/56+10/140+10/260+...+10/1400
Tính tổng
A=10/56+10/140+10/260+...+10/1400
Tính tổng một cách hợp lý:
M = 10/56 + 10/140 + 10/260 + ... + 10/1400
Tính tổng :
H= 10/56 + 10/140 + 10/260 + ... + 10/1400
Tính tổng:A=10/56+10/140+10/260+.........+10/1400
