Các câu hỏi tương tự
CHỨNG MINH : E <9/20 với E=1/5+1/15+1/25+.....+1/1985
Chứng minh rằng:
1/5+1/15+1/25+.....+1/1985 < 9/4
CMR:
1/5 +1/15 +1/25 +...+1/1985 < 9/20
CMR \(\frac{1}{5}+\frac{1}{15}+\frac{1}{25}\) +..................+\(\frac{1}{1985}<\frac{9}{20}\)
chung minh rang 1/10^2+1/15^2+1/20^2+...+1/500^2<1/15
Chứng minh rằng : \(\frac{1}{5}+\frac{1}{15}+\frac{1}{25}+....+\frac{1}{1985}< \frac{9}{20}\)
CMR: \(\frac{1}{5}+\frac{1}{13}+\frac{1}{25}+...+\frac{1}{1985}<\frac{9}{20}\)
Chung minh rang 1/15+1/16+1/17+1/18+.....+1/44 > 5/6
chung minh rang:
1/5+1/13+1/25+1/41+1/61+1/85+1/113<1/2