18/109 < 5/30

52/21 < 523/212

\(\frac{18}{109}\)< \(\frac{5}{30}\)

\(\frac{52}{21}\)<\(\frac{523}{212}\)

\(\frac{18}{91}< \frac{18}{90}=\frac{1}{5}\)

\(\frac{23}{114}>\frac{23}{115}=\frac{1}{5}\)

=> \(\frac{18}{91}< \frac{23}{114}\)

\(\frac{21}{52}=\frac{210}{520}=1-\frac{310}{520}\)

\(\frac{213}{523}=1-\frac{310}{523}\)

Vì \(\frac{310}{520}>\frac{310}{523}\)=> \(1-\frac{310}{520}< 1-\frac{310}{523}\)

=> \(\frac{21}{52}< \frac{213}{523}\)

\(\frac{18}{91}< \frac{18}{90}=\frac{1}{5}=\frac{23}{115}< \frac{23}{114}\)

\(=>\frac{18}{91}< \frac{23}{114}\)

 ok

b)

ta có : \(\frac{1313}{9191}=\frac{13}{91}=\frac{1}{7}\)

\(\frac{1111}{7373}=\frac{11}{73}>\frac{11}{77}\)

Mà \(\frac{11}{77}=\frac{1}{7}\)

\(\Rightarrow\frac{11}{73}>\frac{1}{7}\)

Vậy \(\frac{1313}{9191}< \frac{1111}{7373}\)

1-21/52=31/52     1-213/523=310/523     ta có 31/52=310/520

vì 310/520<310/523 nên 21/52 < 213/523

phần còn lại như bạn bên trên nha! chọn mk nhé!

Tự đi mà làm 

tìm phân số trung gian nhé bạn

đúng k nhé

đừng quên

nếu các bạn trả lời linh tinh thì mình sẽ không tích cho các bạn đâu

tìm phân số trung gian đúng rồi mà

phân số\(\frac{213}{523}\)>\(\frac{21}{52}\)

21/52=21x523/52x523=1092/27196

                          Vì 11076/27196>1092/27196 => 21/52<213/523

213/523=213x52/523x52=11076/27196

sử dụng phép quy đồng để so sánh phân số:

 \(\frac{21}{52}=\frac{213}{523}=\frac{21.523}{52.523}=\frac{11172}{27196}=\frac{2793}{6799}\)

  \(\frac{213}{523}=\frac{21}{52}=\frac{213.52}{523.52}=\frac{11076}{13075}\)Mẫu số ghi nhầm:27196

So sánh 11172 vs 11076 thì:11172>11076

Vậy 21/52>213/523

a) \(\frac{{ - 21}}{{10}}\) < 0

b) \(\frac{{ - 5}}{{ - 2}} = \frac{5}{2} > 0\). Vậy \(\frac{{ - 5}}{{ - 2}} > 0\).

c) \(\frac{{ - 5}}{{ - 2}} = \frac{5}{2} > 0\), mà \(\frac{{ - 21}}{{10}} < 0\)

Vậy \(\frac{{ - 5}}{{ - 2}} > \frac{{ - 21}}{{10}}\).

a: \(-\dfrac{21}{10}< 0\)

b: \(0< -\dfrac{5}{-2}\)

c: \(-\dfrac{21}{10}< 0< \dfrac{-5}{-2}\)

21/52<213/523

a >

b <

c >

d <

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\(a:ta.c\text{ó}:BCNN:12\\ \dfrac{2}{3}=\dfrac{2\cdot4}{3\cdot4}=\dfrac{8}{12};\dfrac{1}{4}=\dfrac{1\cdot3}{4\cdot3}=\dfrac{3}{12}\\ v\text{ì }\dfrac{8}{12}< \dfrac{3}{12}n\text{ê}n\dfrac{2}{3}< \dfrac{1}{4}\\ b:ta.c\text{ó}:\\ 10=2\cdot5\\ 8=2^3\\ \Rightarrow BCNN=2^3\cdot5=8\cdot5=40\\ \dfrac{7}{10}=\dfrac{7\cdot4}{10\cdot4}=\dfrac{28}{40};\dfrac{7}{8}=\dfrac{7\cdot5}{8\cdot5}=\dfrac{35}{40}\\ v\text{ì }\dfrac{28}{40}< \dfrac{35}{40}n\text{ê}n\dfrac{7}{10}< \dfrac{7}{8}\\ c:ta.c\text{ó}:\\ 7=7;5=5\\ \Rightarrow BCNN=7\cdot5=35\\ \dfrac{6}{7}=\dfrac{6\cdot5}{7\cdot5}=\dfrac{30}{35};\dfrac{3}{5}=\dfrac{3\cdot7}{5\cdot7}=\dfrac{21}{35}\\ v\text{ì }\dfrac{30}{35}>\dfrac{21}{35}n\text{ê}n\dfrac{6}{7}>\dfrac{3}{5}\\ d:ta.c\text{ó}:\\ 21=3\cdot7\\ 72=2^3\cdot3^2\\ \Rightarrow BCNN=2^3\cdot3^2\cdot7=504\\ \dfrac{14}{21}=\dfrac{14\cdot24}{21\cdot24}=\dfrac{336}{504};\dfrac{60}{72}=\dfrac{60\cdot7}{72\cdot7}=\dfrac{420}{504}\\ v\text{ì }\dfrac{336}{504}< \dfrac{420}{504}n\text{ê}n\dfrac{14}{21}< \dfrac{60}{72}\)