Question

[Con gái thời hiện đại ngại gì FA]

Bài tập: So sánh:

a, \(\dfrac{12}{49}\&\dfrac{13}{47}\)

\(b,\dfrac{64}{85}\&\dfrac{17}{35}\)

\(c,\dfrac{19}{31}\&\dfrac{17}{35}\)

(Gợi ý: a,b,c: Phân số chung gian)

\(d,\dfrac{67}{77}\&\dfrac{73}{83}\)

\(e,\dfrac{456}{461}\&\dfrac{123}{128}\)

(Gợi ý: d, e:Phần bù đến đơn vị)

Answer 1

[Mashiro Shiina]

a)\(12< 13;49>47\)

\(\Rightarrow\dfrac{12}{49}< \dfrac{13}{47}\)

b)\(\dfrac{64}{85}>\dfrac{43}{85}\Rightarrow\dfrac{64}{85}>\dfrac{1}{2}\)

\(\dfrac{17}{35}< \dfrac{17}{34}\Rightarrow\dfrac{17}{35}< \dfrac{1}{2}\)

\(\Rightarrow\dfrac{17}{35}< \dfrac{64}{85}\)

c) \(\dfrac{19}{31}>\dfrac{16}{31}\Rightarrow\dfrac{19}{31}>\dfrac{1}{2}\)

\(\dfrac{17}{35}< \dfrac{17}{34}\Rightarrow\dfrac{17}{35}< \dfrac{1}{2}\)

\(\Rightarrow\dfrac{17}{35}< \dfrac{19}{31}\)

d)

\(1-\dfrac{67}{77}=\dfrac{10}{77}\)

\(1-\dfrac{73}{83}=\dfrac{10}{83}\)

\(\dfrac{10}{77}>\dfrac{10}{83}\Rightarrow\dfrac{67}{77}< \dfrac{73}{83}\)

e)\(1-\dfrac{456}{461}=\dfrac{5}{461}\)

\(1-\dfrac{123}{128}=\dfrac{5}{128}\)

\(\dfrac{5}{461}< \dfrac{5}{128}\Rightarrow\dfrac{456}{461}>\dfrac{123}{128}\)

Answer 2

[Nguyễn Thị Giang Thanh]

\(a,\dfrac{12}{49}< \dfrac{12}{47}< \dfrac{13}{47}\Rightarrow\dfrac{12}{49}< \dfrac{12}{47}\)

b, Ta có: \(\dfrac{17}{35}=\dfrac{51}{105}\)

\(\dfrac{64}{85}>\dfrac{64}{105}>\dfrac{51}{105}\Rightarrow\dfrac{64}{85}>\dfrac{51}{105}\) hay \(\dfrac{64}{85}>\dfrac{17}{85}\)

c,\(\dfrac{19}{31}>\dfrac{17}{31}>\dfrac{17}{35}\Rightarrow\dfrac{19}{31}>\dfrac{17}{35}\)

d, \(\dfrac{67}{77}+\dfrac{10}{77}=1\)

\(\dfrac{73}{83}+\dfrac{10}{83}=1\)

\(\dfrac{10}{77}>\dfrac{10}{83}\Rightarrow\dfrac{67}{77}< \dfrac{73}{83}\)

e, \(\dfrac{456}{461}+\dfrac{5}{461}=1\)

\(\dfrac{123}{128}+\dfrac{5}{128}=1\)

\(\dfrac{5}{461}< \dfrac{5}{128}\Rightarrow\dfrac{456}{461}>\dfrac{123}{128}\)