B=1/4+(1/5+1/6+...+1/9)+(1/10+1/11+...+1/19)
Vì 1/5+1/6+...+1/9>1/9+1/9+...1/9 nên 1/5+1/6+...+1/9>5/9>1/2
Vì 1/10+1/11+...+1/19>1/19+1/19+...+1/9 nên 1/10+1/11+...+1/19>10/19>1/2
=> B>1/4+1/2+1/2>1
\(B=\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{19}\)
CHỨNG MINH RẰNG B > 1
các bạn giải đầy đủ hộ mình nhớ giải thích rõ ràng nhé mình cảm ơn
B=\(\frac{1}{4}+\frac{1}{5}+....+\frac{1}{19}\)
Chứng tỏ B > 1
\(\left(19-\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)
CMR: \(\frac{1}{6}<\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{100^2}<\frac{1}{4}\)
\(\frac{\left(27\frac{5}{19}-26\frac{4}{13}\right).\left(\frac{3}{4}+\frac{19}{59}-\frac{3}{118}\right)}{\left(\frac{3}{4}+x\right)\frac{27}{33}}\) =1. Tìm x
CTR :
\(B=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+\frac{1}{8^2}< 1\)
Tìm x:
\(x.\frac{1}{2}-x.\frac{2}{3}+x.\frac{3}{4}-x.\frac{5}{6}=\frac{5}{6}-\frac{3}{4}+\frac{2}{3}-\frac{1}{2}\)
help me pleas
Tính B=$\frac{1}{3} \frac{1}{6}\left(1 2\right) \frac{1}{9}\left(1 2 3\right) ... \frac{1}{6045}\left(1 2 3 ... 2015\right)$13 16 (1 2) 19 (1 2 3) ... 16045 (1 2 3 ... 2015)
