Cho 1/M=1/(1+2+3) + 1/(1+2+3+4) +.....+ 1/(1+2+3+4+...+59)
Chứng minh rằng M>2/3
chứng minh m=1/1+2+3+1/1+2+3+4+1/1+2+3+4+5+...1/1+2+3+...+59 <2/3
Cho \(M=\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+...+\frac{1}{1+2+3+...+59}\)
Chứng minh: M<2/3
1. Chứng minh: \(\left(2^1+2^2+2^3+2^4+...+2^{59}+2^{60}\right):3\)
2. Chứng minh: \(M=3^{n+3}+3^{n+1}+2^{n+3}+2^{n+2}⋮6\)
CHO
\(\frac{1}{M}=\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+\frac{1}{1+2+3+4+5}+...+\frac{1}{1+2+3+...+59}\)
Chứng minh rằng M>\(\frac{2}{3}\)
Cho M =\(\frac{1}{1+2+3}\)+\(\frac{1}{1+2+3+4}\)+..............................+\(\frac{1}{1+2+3+..........+59}\)
Chứng minh M<\(\frac{2}{3}\)
\(ChoM+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+....+\frac{1}{1+2+3+4+...+59}.\)
Chứng minh rằng \(M< \frac{2}{3}\)
M=\(\frac{1}{1+2+3}\)+\(\frac{1}{1+2+3+4}\)+..............+\(\frac{1}{1+2+3+...+59}\)
chứng minh M<\(\frac{2}{3}\)
Cho M= 1/1+2+3 + 1/1+2+3+4 + ... +1/1+2+3+...+59
CMR: M<2/3
