Câu hỏi của Nguyễn Trà My

Question

SO SÁNH:a)$\frac{18}{91}$    và   $\frac{23}{114}$b)$\frac{21}{52}$    và   $\frac{213}{523}$c)$\frac{1313}{9191}$và  $\frac{1111}{7373}$d)$\frac{n}{n+1}$và  $\frac{n+2}{n+3}$ai đúng m...

Huy hoàng indonaca · Accepted Answer

a) Ta có :$\frac{18}{91}< \frac{18}{90}=\frac{1}{5}=\frac{23}{115}< \frac{23}{114}$$\Rightarrow\frac{18}{91}< \frac{23}{114}$b) Ta có :$\frac{21}{52}=\frac{210}{520}=1-\frac{310}{520}$$\frac{213}{523}=1-\frac{310}{523}$Mà $1-\frac{310}{520}< 1-\frac{310}{523}$$\Rightarrow\frac{21}{52}< \frac{213}{523}$c) Ta có : $\frac{1313}{9191}=\frac{13}{91}=\frac{1}{7}=\frac{11}{77};\frac{1111}{7373}=\frac{11}{73}$Mà $\frac{11}{77}< \frac{11}{73}$nên $\frac{1313}{9191}< \frac{1111}{7373}$d) Ta có :$\frac{n}{n+1}=\frac{n+1-1}{n+1}=1-\frac{1}{n+1}$$\frac{n+2}{n+3}=\frac{n+3-1}{n+3}=1-\frac{1}{n+3}$Mà $1-\frac{1}{n+1}< 1-\frac{1}{n+3}$nên $\frac{n}{n+1}< \frac{n+2}{n+3}$Câu trả lời: a) Ta có :$\frac{18}{91}< \frac{18}{90}=\frac{1}{5}=\frac{23}{115}< \frac{23}{114}$$\Rightarrow\frac{18}{91}< \frac{23}{114}$b) Ta có :$\frac{21}{52}=\frac{210}{520}=1-\frac{310}{520}$$\frac{213}{523}=1-\frac{310}{523}$Mà $1-\frac{310}{520}< 1-\frac{310}{523}$$\Rightarrow\frac{21}{52}< \frac{213}{523}$c) Ta có : $\frac{1313}{9191}=\frac{13}{91}=\frac{1}{7}=\frac{11}{77};\frac{1111}{7373}=\frac{11}{73}$Mà $\frac{11}{77}< \frac{11}{73}$nên $\frac{1313}{9191}< \frac{1111}{7373}$d) Ta có :$\frac{n}{n+1}=\frac{n+1-1}{n+1}=1-\frac{1}{n+1}$$\frac{n+2}{n+3}=\frac{n+3-1}{n+3}=1-\frac{1}{n+3}$Mà $1-\frac{1}{n+1}< 1-\frac{1}{n+3}$nên $\frac{n}{n+1}< \frac{n+2}{n+3}$

#❤️_Tiểu-La_❤️# · Answer

a) Ta có : $\frac{18}{91}< \frac{18}{90}=\frac{1}{5}< \frac{23}{115}< \frac{23}{114}$$\Rightarrow$ $\frac{18}{91}< \frac{23}{114}$Vậy $\frac{18}{91}< \frac{23}{114}$b) Ta có : $\frac{21}{52}< \frac{21}{56}=\frac{3}{8}< \frac{213}{568}< \frac{213}{523}$$\Rightarrow$ $\frac{21}{52}< \frac{213}{523}$Vậy $\frac{21}{52}< \frac{213}{523}$c) Ta có : $\frac{1313}{9191}=\frac{1313:1313}{9191:1313}=\frac{1}{7}$ $\frac{1111}{7373}=\frac{1111:101}{7373:101}=\frac{11}{73}$ Lại có : $\frac{1}{7}< \frac{11}{77}< \frac{11}{73}$$\Rightarrow$ $\frac{1313}{9191}< \frac{1111}{7373}$Vậy $\frac{1313}{9191}< \frac{1111}{7373}$d) Ta có : $1-\frac{n}{n+1}=\frac{n+1}{n+1}-\frac{n}{n+1}=\frac{1}{n+1}$ $1-\frac{n+2}{n+3}=\frac{n+3}{n+3}-\frac{n+2}{n+3}=\frac{1}{n+3}$ Vì $n+1< n+3$$\Rightarrow$$\frac{1}{n+1}>\frac{1}{n+3}$$\Rightarrow$ $\frac{n}{n+1}< \frac{n+2}{n+3}$Vậy $\frac{n}{n+1}< \frac{n+2}{n+3}$ Chúc m.n hok tốt ♡❤️Câu trả lời: a) Ta có : $\frac{18}{91}< \frac{18}{90}=\frac{1}{5}< \frac{23}{115}< \frac{23}{114}$$\Rightarrow$ $\frac{18}{91}< \frac{23}{114}$Vậy $\frac{18}{91}< \frac{23}{114}$b) Ta có : $\frac{21}{52}< \frac{21}{56}=\frac{3}{8}< \frac{213}{568}< \frac{213}{523}$$\Rightarrow$ $\frac{21}{52}< \frac{213}{523}$Vậy $\frac{21}{52}< \frac{213}{523}$c) Ta có : $\frac{1313}{9191}=\frac{1313:1313}{9191:1313}=\frac{1}{7}$ $\frac{1111}{7373}=\frac{1111:101}{7373:101}=\frac{11}{73}$ Lại có : $\frac{1}{7}< \frac{11}{77}< \frac{11}{73}$$\Rightarrow$ $\frac{1313}{9191}< \frac{1111}{7373}$Vậy $\frac{1313}{9191}< \frac{1111}{7373}$d) Ta có : $1-\frac{n}{n+1}=\frac{n+1}{n+1}-\frac{n}{n+1}=\frac{1}{n+1}$ $1-\frac{n+2}{n+3}=\frac{n+3}{n+3}-\frac{n+2}{n+3}=\frac{1}{n+3}$ Vì $n+1< n+3$$\Rightarrow$$\frac{1}{n+1}>\frac{1}{n+3}$$\Rightarrow$ $\frac{n}{n+1}< \frac{n+2}{n+3}$Vậy $\frac{n}{n+1}< \frac{n+2}{n+3}$ Chúc m.n hok tốt ♡❤️

Arima Kousei · Answer

P/s : a)Ta có : $\frac{18}{91}< \frac{18}{90}=\frac{1}{5}< \frac{23}{115}< \frac{23}{114}$$\Rightarrow$ $\frac{18}{91}< \frac{23}{114}$Vậy $\frac{18}{91}< \frac{23}{114}$b)Ta có : $\frac{21}{52}< \frac{21}{56}=\frac{3}{8}< \frac{213}{568}< \frac{213}{523}$$\Rightarrow$ $\frac{21}{52}< \frac{213}{523}$Vậy $\frac{21}{52}< \frac{213}{523}$c)Ta có : $\frac{1313}{9191}=\frac{1313:1313}{9191:1313}=\frac{1}{7}$ $\frac{1111}{7373}=\frac{1111:101}{7373:101}=\frac{11}{73}$ Lại có : $\frac{1}{7}< \frac{11}{77}< \frac{11}{73}$$\Rightarrow$ $\frac{1313}{9191}< \frac{1111}{7373}$Vậy $\frac{1313}{9191}< \frac{1111}{7373}$d ) Ta có : $\frac{n}{n+1}=\frac{n+1-1}{n+1}=1-\frac{1}{n+1}$$\frac{n+2}{n+3}=\frac{n+3-1}{n+3}=1-\frac{1}{n+3}$Do $\frac{1}{n+1}>\frac{1}{n+3}\left(n+1< n+3\right)$$\Rightarrow1-\frac{1}{n+1}>1-\frac{1}{n+3}$$\Rightarrow\frac{n}{n+1}>\frac{n+2}{n+3}$Vậy ...~ Ủng hộ nha Câu trả lời: P/s : a)Ta có : $\frac{18}{91}< \frac{18}{90}=\frac{1}{5}< \frac{23}{115}< \frac{23}{114}$$\Rightarrow$ $\frac{18}{91}< \frac{23}{114}$Vậy $\frac{18}{91}< \frac{23}{114}$b)Ta có : $\frac{21}{52}< \frac{21}{56}=\frac{3}{8}< \frac{213}{568}< \frac{213}{523}$$\Rightarrow$ $\frac{21}{52}< \frac{213}{523}$Vậy $\frac{21}{52}< \frac{213}{523}$c)Ta có : $\frac{1313}{9191}=\frac{1313:1313}{9191:1313}=\frac{1}{7}$ $\frac{1111}{7373}=\frac{1111:101}{7373:101}=\frac{11}{73}$ Lại có : $\frac{1}{7}< \frac{11}{77}< \frac{11}{73}$$\Rightarrow$ $\frac{1313}{9191}< \frac{1111}{7373}$Vậy $\frac{1313}{9191}< \frac{1111}{7373}$d ) Ta có : $\frac{n}{n+1}=\frac{n+1-1}{n+1}=1-\frac{1}{n+1}$$\frac{n+2}{n+3}=\frac{n+3-1}{n+3}=1-\frac{1}{n+3}$Do $\frac{1}{n+1}>\frac{1}{n+3}\left(n+1< n+3\right)$$\Rightarrow1-\frac{1}{n+1}>1-\frac{1}{n+3}$$\Rightarrow\frac{n}{n+1}>\frac{n+2}{n+3}$Vậy ...~ Ủng hộ nha

Khoá học trên OLM (olm.vn)

Khoá học trên OLM (olm.vn)