![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giả sử a > = b ko làm mất đi tính tổng quát của bài toán.
=> a= m+b (m>=0)
Ta có: \(\frac{a}{b}+\frac{b}{a}\)= \(\frac{b+m}{b}\)+ \(\frac{b}{b+m}\)=1 + \(\frac{m}{b}\)+\(\frac{b}{b+m}\)< 1 + \(\frac{m}{b+m}\)+\(\frac{b}{b+m}\)= 1 + \(\frac{m+b}{b+m}\)= 1+1=2
Vậy a/b + b/a < 2 (ĐPCM)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(45\cdot\left(-\frac{5}{7}\right)+9\cdot5+\frac{8}{9}+135+45\cdot\frac{52}{63}\)
\(=-\frac{225}{7}+45+\frac{8}{9}+135+\frac{260}{7}\)
\(=\left(-\frac{225}{7}+\frac{260}{7}\right)+\left(45+135\right)+\frac{8}{9}\)
\(=\frac{35}{7}+180+\frac{8}{9}\)
\(=5+180+\frac{8}{9}\)
\(=185+\frac{8}{9}=185\frac{8}{9}\)
tick đúng cho tớ nha
![](https://rs.olm.vn/images/avt/0.png?1311)
\(80-\frac{1}{9}-\frac{2}{10}-\frac{3}{11}-...-\frac{80}{88}=\left(1-\frac{1}{9}\right)+\left(1-\frac{2}{10}\right)+\left(1-\frac{3}{11}\right)+...+\left(1-\frac{80}{88}\right)\)
\(=\frac{8}{9}+\frac{8}{10}+\frac{8}{11}+...+\frac{8}{88}=8.\left(\frac{1}{9}+\frac{1}{10}+\frac{1}{11}+\frac{1}{88}\right)\)
\(\frac{1}{45}+\frac{1}{50}+\frac{1}{55}+...+\frac{1}{440}=\frac{1}{5}\left(\frac{1}{9}+\frac{1}{10}+\frac{1}{11}+...+\frac{1}{88}\right)\)
=>B=8:1/5=40