So sánh phân số: 5/11 và 3/21

a)

\(\frac{3}{21}=\frac{1}{7}\)

\(1-\frac{5}{11}=\frac{6}{11}\)

\(1-\frac{1}{7}=\frac{6}{7}\)

Ta có: \(\frac{6}{11}<\frac{6}{7}\ nên\ \frac{5}{11}>\frac{3}{21}\)

b) \(\frac{-3}{5}<1;\ \frac{5}{3}>1\)

=> \(\frac{-3}{5}<\frac{5}{3}\)

c) 5/4 >1

4/5 <1

=> 4/5 < 5/4

d) \(\frac{-2}{11}<0\)

\(\frac{-3}{-4}=\frac{3}{4}>0\)

=> \(\frac{-2}{11}<\frac{-3}{-4}\)

e) \(1-\frac{11}{12}=\frac{1}{12};\ 1-\frac{12}{13}=\frac{1}{13}\)

\(\frac{1}{12}>\frac{1}{13}\ nên\ \frac{-11}{12}>\frac{-12}{13}\)

g) - 3/2 < 0 và 5/6 > 0

=> - 3/2 < 5/6

h) \(1-\frac{4}{5}=\frac{1}{5};\ 1-\frac{6}{7}=\frac{1}{7}\)

=> \(\frac{1}{5}>\frac{1}{7}nên\ \frac{4}{5}<\frac{6}{7}\)