Ta có : \(\frac{5}{11}+\frac{5}{12}+\frac{5}{13}+\frac{5}{14}\)
\(=5.\left(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+\frac{1}{14}\right)\)
\(< 5.\left(\frac{1}{11}+\frac{1}{11}+\frac{1}{11}+\frac{1}{11}\right)\)
\(=5.\frac{4}{11}\)
\(=\frac{20}{11}< \frac{20}{10}< 2\)
Vậy \(\frac{5}{11}+\frac{5}{12}+\frac{5}{13}+\frac{5}{14}< 2\left(đpcm\right)\)
5/11=5/11
5/12<5/11
5/13<5/11
5/14<5/11
=> 5/11+5/12+5/13+5/14<5/11*4=20/11<20/10=2
vậy 5/11+5/12+5/13=5/14<2
study well
k nha
ai k đúng cho mk mk trả lại gấp đôi
Bài giải
Ta có : \(\frac{5}{11}+\frac{5}{12}+\frac{5}{13}+\frac{5}{14}=5\left(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+\frac{1}{14}\right)< 5\left(\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\right)=5\cdot\frac{4}{10}=\frac{20}{10}=2\)\(\Rightarrow\text{ ĐPCM}\)
Bài giải
Ta có : \(\frac{5}{11}+\frac{5}{12}+\frac{5}{13}+\frac{5}{14}=5\left(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+\frac{1}{14}\right)< 5\left(\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\right)=5\cdot\frac{4}{10}=\frac{20}{10}=2\)\(\Rightarrow\text{ ĐPCM}\)