CMR:1+1/2+1/3+...+1/21999>1000
Chứng tỏ rằng
1+1/2+1/3+.......+1/21999>1000
CMR 1+1/2+1/3+.......+1/2^1999 >1000
CMR: 1+1/2+1/3+......1/2^2015<1000
cmr :1+1/2+1/3+...+1/2 mũ 1999>1000
Câu hỏi: CMR: 1+1/2+1/3+....1/2^1999 >1000
cmr: 1/2!+1/3!+1/4!+...+1/1000! không phải là số tự nhiên
CMR: (1/22-1) (1/32-1).....(1/1002-1)<1/1000
CMR:1-1/2+1/+-1/4+1/5-1/6+...+1/999-1/1000=1/501+1/502+1/503+1/504+...+1/1000
\(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+........+\frac{1}{999}-\frac{1}{1000}\)
\(=1+\frac{1}{2}+\frac{1}{3}+.......+\frac{1}{999}+\frac{1}{1000}-2\left(\frac{1}{2}+\frac{1}{4}+......+\frac{1}{1000}\right)\)
\(=1+\frac{1}{2}+\frac{1}{3}+.........+\frac{1}{999}+\frac{1}{1000}-1-\frac{1}{2}-......-\frac{1}{500}\)
\(=\frac{1}{501}+\frac{1}{502}+.......+\frac{1}{1000}\)
\(\Rightarrowđpcm\)
1)CMR :1+12+1/3+..+1/2^1999<1000
2)tím số tự nhiên x biết :1/3+1/3+1/10+...+1/x(x+1)=2013/2015