Bài 2:
a: 5/7=20/28
3/4=21/28
mà 20/28<21/28
nên 5/7<3/4
b: 8/9=16/18
5/6=15/18
mà 16/18>15/18
nên 8/9>5/6
Bài 2:
\(a,\dfrac{5}{7}=\dfrac{20}{28};\dfrac{3}{4}=\dfrac{21}{28}\\\Rightarrow\dfrac{20}{28}< \dfrac{21}{28}\\ \Rightarrow\dfrac{5}{7}< \dfrac{3}{4}\)
\(b,\dfrac{8}{9}=\dfrac{48}{54};\dfrac{5}{6}=\dfrac{45}{54}\\ \Rightarrow\dfrac{48}{54}>\dfrac{45}{54}\\ \Rightarrow\dfrac{8}{9}>\dfrac{5}{6}\)
Bài 1: a, \(\dfrac{25}{50}+\dfrac{5}{15}=\dfrac{1}{2}+\dfrac{1}{3}=\dfrac{5}{6}\)
b, \(\dfrac{72}{90}+\dfrac{7}{28}=\dfrac{4}{5}+\dfrac{1}{4}=\dfrac{21}{20}\)
c,\(\dfrac{32}{96}+\dfrac{8}{28}=\dfrac{1}{3}+\dfrac{2}{7}=\dfrac{13}{21}\)
Bài 2: \(\dfrac{5}{7}< \dfrac{3}{4}\) \(\dfrac{8}{9}>\dfrac{5}{6}\)
