M = 10/56 + 10/140 + 10/260 +...+ 10/1400
M = 5/28 + 5/70 + 5/130 + ... + 5/700
M = 5/4.7 + 5/7.10 + 5/10.13 + ... + 5/25.28
M = 5.1/3.(3/4.7 + 3/7.10 + 3/10.13 + ... + 3/25.28)
M = 5/3.(1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 + ... + 1/25 - 1/28)
M = 5/3.(1/4 - 1/28)
M = 5/3.3/14
M = 5/14
M=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+.....+\frac{10}{1400}\)
tính tổng M
Tính B=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+.....+\frac{10}{1400}\)
Tính: \(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Tính tổng
S=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
tính \(B=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Tính : D=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Tính tổng:
\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Tính hợp lí(nếu có thể)
E=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Tính tổng M
\(M=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
b) tìm x,y biết
\(2^x+624=5y\)
