Cm:1\5+1/15+1/25+...+1/1985<9/20
CMR : 1/5 + 1/15 + 1/25 +....+1/1985 <9/20
Chứng minh 1/5 + 1/15 + 1/25 +......+ 1/1985 < 9/20
Chứng minh rằng: 1/5 +1/15 +1/25 +.......+1/1985 <9/20
CMR: 1/5+1/15+1/25+...+1/1985 <9/20
Chứng minh rằng 1/5 + 1/15 + 1/25 + ... + 1/1985 < 9/20
Chứng minh rằng: 1/5 + 1/ 15 + 1/ 25 +......+ 1/1985 < 9/ 20
Chứng minh rằng: 1/5+1/15+1/25+...+1/1985<9/20
Chứng minh rằng: 1/5+1/15+1/25+...+1/1985<9/20