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a; Cách một:
\(\dfrac{2}{9}\) = \(\dfrac{2\times2}{9\times2}\) = \(\dfrac{4}{18}\) < \(\dfrac{4}{10}\) Vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)
\(\dfrac{4}{9}\) = \(\dfrac{4\times3}{9\times3}\) = \(\dfrac{12}{27}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times2}{10\times2}\) = \(\dfrac{12}{20}\)
Vì \(\dfrac{12}{27}\) < \(\dfrac{12}{20}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{12}{20}\)
\(\dfrac{3}{8}\) = \(\dfrac{3\times4}{8\times4}\) = \(\dfrac{12}{24}\); \(\dfrac{4}{7}\) = \(\dfrac{4\times3}{7\times3}\) = \(\dfrac{12}{21}\)
Vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)
\(\dfrac{5}{9}\) = \(\dfrac{5\times7}{9\times7}\) = \(\dfrac{35}{63}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times5}{10\times5}\) = \(\dfrac{35}{50}\)
Vì \(\dfrac{35}{63}\) < \(\dfrac{35}{50}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)
Cách hai:
a; \(\dfrac{2}{9}\) = \(\dfrac{2\times10}{9\times10}\) = \(\dfrac{20}{90}\); \(\dfrac{4}{10}\) = \(\dfrac{4\times9}{10\times9}\) = \(\dfrac{36}{90}\)
Vì \(\dfrac{20}{90}\) < \(\dfrac{36}{90}\) vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)
b; \(\dfrac{4}{9}\) = \(\dfrac{4\times10}{9\times10}\) = \(\dfrac{40}{90}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times9}{10\times9}\) = \(\dfrac{54}{90}\)
Vì \(\dfrac{40}{90}\) < \(\dfrac{54}{90}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{6}{10}\)
c; \(\dfrac{3}{8}\) = \(\dfrac{3\times7}{8\times7}\) = \(\dfrac{21}{56}\); \(\dfrac{4}{7}\) = \(\dfrac{4\times8}{7\times8}\) = \(\dfrac{32}{56}\)
Vì \(\dfrac{21}{56}\) < \(\dfrac{32}{56}\) vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)
d; \(\dfrac{5}{9}\) = \(\dfrac{5\times10}{9\times10}\) = \(\dfrac{50}{90}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times9}{10\times9}\) = \(\dfrac{63}{90}\)
Vì \(\dfrac{50}{90}\) < \(\dfrac{63}{90}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)
A , 34 - \(\dfrac{x}{30}\) = \(\dfrac{5}{6}\)
\(\dfrac{x}{30}\) = 34 - \(\dfrac{5}{6}\)
\(\dfrac{x}{30}=\) \(\dfrac{199}{6}\)
\(\dfrac{x}{30}=\) \(\dfrac{995}{30}\)
x = 995
B x +\(\dfrac{13}{34}\) = \(\dfrac{12}{17}\)
x = \(\dfrac{12}{17}-\dfrac{13}{34}\)
x = \(\dfrac{11}{34}\)
\(\dfrac{7}{9}=\dfrac{21}{27};\dfrac{7}{10}=\dfrac{21}{30}\)
hai số nằm giữa \(\dfrac{7}{9}\) và \(\dfrac{7}{10}\)
\(\dfrac{21}{27}>\dfrac{21}{28}>\dfrac{21}{29}>\dfrac{21}{30}\)
a; Cách một:
\(\dfrac{2}{9}\) = \(\dfrac{2\times2}{9\times2}\) = \(\dfrac{4}{18}\) < \(\dfrac{4}{10}\) Vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)
\(\dfrac{4}{9}\) = \(\dfrac{4\times3}{9\times3}\) = \(\dfrac{12}{27}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times2}{10\times2}\) = \(\dfrac{12}{20}\)
Vì \(\dfrac{12}{27}\) < \(\dfrac{12}{20}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{12}{20}\)
\(\dfrac{3}{8}\) = \(\dfrac{3\times4}{8\times4}\) = \(\dfrac{12}{24}\); \(\dfrac{4}{7}\) = \(\dfrac{4\times3}{7\times3}\) = \(\dfrac{12}{21}\)
Vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)
\(\dfrac{5}{9}\) = \(\dfrac{5\times7}{9\times7}\) = \(\dfrac{35}{63}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times5}{10\times5}\) = \(\dfrac{35}{50}\)
Vì \(\dfrac{35}{63}\) < \(\dfrac{35}{50}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)
Cách hai:
a; \(\dfrac{2}{9}\) = \(\dfrac{2\times10}{9\times10}\) = \(\dfrac{20}{90}\); \(\dfrac{4}{10}\) = \(\dfrac{4\times9}{10\times9}\) = \(\dfrac{36}{90}\)
Vì \(\dfrac{20}{90}\) < \(\dfrac{36}{90}\) vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)
b; \(\dfrac{4}{9}\) = \(\dfrac{4\times10}{9\times10}\) = \(\dfrac{40}{90}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times9}{10\times9}\) = \(\dfrac{54}{90}\)
Vì \(\dfrac{40}{90}\) < \(\dfrac{54}{90}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{6}{10}\)
c; \(\dfrac{3}{8}\) = \(\dfrac{3\times7}{8\times7}\) = \(\dfrac{21}{56}\); \(\dfrac{4}{7}\) = \(\dfrac{4\times8}{7\times8}\) = \(\dfrac{32}{56}\)
Vì \(\dfrac{21}{56}\) < \(\dfrac{32}{56}\) vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)
d; \(\dfrac{5}{9}\) = \(\dfrac{5\times10}{9\times10}\) = \(\dfrac{50}{90}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times9}{10\times9}\) = \(\dfrac{63}{90}\)
Vì \(\dfrac{50}{90}\) < \(\dfrac{63}{90}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)
Mk làm câu \(a\) thôi nha
\(a,\)\(\dfrac{4}{7}\) và \(\dfrac{34}{7}\)
Ta xét mẫu của hai phân số và thấy mẫu giống nhau.Từ đó,ta có thể kết luận:
\(=>\)Đây là so sánh các phân số cùng mẫu số
\(+\)So sánh các phân số cùng mẫu số
\(-\)Nếu tử số lớn hơn thì lớn hơn
\(-\)Tử số bé hơn thì bé hơn
\(-\)Tử số bằng nhau thì cả hai phân số bằng nhau
Ta xét tử hai phân số và thấy:
\(4< 34\)
Từ đó ta có thể kết luận:
\(\dfrac{4}{7}< \dfrac{34}{7}\)
b) \(\dfrac{103}{271}\) và \(\dfrac{130}{217}\)
Ta xét phân số trung gian của \(\dfrac{103}{271}\) và \(\dfrac{130}{217}\) là \(\dfrac{103}{217}\)
Vì: \(\dfrac{103}{271}\) < \(\dfrac{103}{217}\) và \(\dfrac{130}{217}\) > \(\dfrac{103}{217}\)
\(\Rightarrow\) \(\dfrac{103}{271}\) < \(\dfrac{130}{217}\)
a) \(\dfrac{13}{15}< \dfrac{14}{15}\) ( vì 13 < 14 )
b) Ta có:
\(\dfrac{2}{3}=\dfrac{2\times3}{3\times3}=\dfrac{6}{9}\)
Vì 6 = 6 nên \(\dfrac{6}{9}=\dfrac{6}{9}\)
Vậy \(\dfrac{2}{3}=\dfrac{6}{9}\)
c) Ta có:
\(\dfrac{4}{7}=\dfrac{4\times6}{7\times6}=\dfrac{24}{42}\)
\(\dfrac{5}{6}=\dfrac{5\times7}{6\times7}=\dfrac{35}{42}\)
Vì 24 < 35 nên \(\dfrac{24}{42}< \dfrac{35}{42}\)
Vậy \(\dfrac{4}{7}< \dfrac{5}{6}\)
d) Vì 9 < 13 nên \(\dfrac{4}{9}>\dfrac{4}{13}\)
Vậy \(\dfrac{4}{9}>\dfrac{4}{13}\)
a ) 3/4 > 3/7 ( vì 4 < 7 )
b ) 5/4 > 4/4 ( vì 5 > 4 )
=> 5/4 > 1
c ) 13/17 < 17/17 ( vì 13 < 17 )
=> 13/17 < 1
d 5/7 < 6/7
( vì 5 < 6 )
Tham khảo nha !!! Chúc học tốt !!!
a ) 3/4 > 3/7 ( vì 4 < 7 )
b ) 5/4 > 4/4 ( vì 5 > 4 )
=> 5/4 > 1
c ) 13/17 < 17/17 ( vì 13 < 17 )
=> 13/17 < 1
d 5/7 < 6/7
( vì 5 < 6 )