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
1/M=1/1+2+3+1/1+2+3+4+1/1+2+3+4+5+...+1/1+2+3+4+..+59
cmr M>2/3
Cho 1/M=1/(1+2+3) + 1/(1+2+3+4) +.....+ 1/(1+2+3+4+...+59)
Chứng minh rằng M>2/3
M= \(\dfrac{1}{1+2+3}\)+\(\dfrac{1}{1+2+3+4}\)+...+\(\dfrac{1}{1+2+3+...+59}\) CMR M<\(\dfrac{2}{3}\)
1/1+2+3+1/1+2+3+4+...+1/1+2+3+...+59<2/3
Help me, please!
Cho M= 1/1+2+3 + 1/1+2+3+4 + ... +1/1+2+3+...+59
CMR: M<2/3
1) Cho
1/M=1/1+2+3+1/1+2+3+4+..+1/1+2+3+..+59
CMR M>2/3
\(\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+....+\frac{1}{1+2+3+..+59}< \frac{2}{3}\)
Cho M=(1/1+2+3)+(1/1+2+3+4)+...+(1/1+2+3+...+59) . Chứng minh M<2/3