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a)
Ta có: \(BCNN\left( {10,15} \right) = 30\) nên
\(\begin{array}{l}\dfrac{7}{{10}} = \dfrac{{7.3}}{{10.3}} = \dfrac{{21}}{{30}}\\\dfrac{{11}}{{15}} = \dfrac{{11.2}}{{15.2}} = \dfrac{{22}}{{30}}\end{array}\)
Vì \(21 < 22\) nên \(\dfrac{{21}}{{30}} < \dfrac{{22}}{{30}}\) do đó \(\dfrac{7}{{10}} < \dfrac{{11}}{{15}}\).
b)
Ta có: \(BCNN\left( {8,24} \right) = 24\) nên
\(\dfrac{{ - 1}}{8} = \dfrac{{ - 1.3}}{{8.3}} = \dfrac{{ - 3}}{{24}}\)
Vì \( - 3 > - 5\) nên \(\dfrac{{ - 3}}{{24}} > \dfrac{{ - 5}}{{24}}\) do đó \(\dfrac{{ - 1}}{8} > \dfrac{{ - 5}}{{24}}\).
2/
a/ \(\dfrac{7}{10}=\dfrac{7.15}{10.15}=\dfrac{105}{150}\)
\(\dfrac{11}{15}=\dfrac{11.10}{15.10}=\dfrac{110}{150}\)
-Vì \(\dfrac{105}{150}< \dfrac{110}{150}\)(105<110)nên \(\dfrac{7}{10}< \dfrac{11}{15}\)
b/ \(\dfrac{-1}{8}=\dfrac{-1.3}{8.3}=\dfrac{-3}{24}\)
-Vì \(\dfrac{-3}{24}>\dfrac{-5}{24}\left(-3>-5\right)\)nên\(\dfrac{-1}{8}>\dfrac{-5}{24}\)
c/\(\dfrac{25}{100}=\dfrac{25:25}{100:25}=\dfrac{1}{4}\)
\(\dfrac{10}{40}=\dfrac{10:10}{40:10}=\dfrac{1}{4}\)
-Vì \(\dfrac{1}{4}=\dfrac{1}{4}\)nên\(\dfrac{25}{100}=\dfrac{10}{40}\)
a/ \(\dfrac{7}{10}< \dfrac{11}{15}\)
c/ \(\dfrac{25}{100}=\dfrac{10}{40}\)
1. a, \(\frac{6}{7}\)=\(\frac{60}{70}\);\(\frac{11}{10}\)=\(\frac{77}{70}\)
vì \(\frac{60}{70}\)<\(\frac{77}{70}\)nên \(\frac{6}{7}\)<\(\frac{11}{10}\)
b, \(\frac{-5}{17}\)<0<\(\frac{2}{7}\)
c, \(\frac{419}{-723}\)<0<\(\frac{-697}{-313}\)
2.
Ta có :\(\frac{2}{6}\)=\(\frac{20}{60}\);\(\frac{5}{12}\)=\(\frac{25}{60}\);\(\frac{4}{15}\)=\(\frac{16}{60}\);\(\frac{8}{20}\)=\(\frac{24}{60}\);\(\frac{10}{30}\)=\(\frac{20}{60}\)
Vì \(\frac{16}{60}\)<\(\frac{20}{60}\)<\(\frac{24}{60}\)<\(\frac{25}{60}\)nên \(\frac{4}{15}\)<\(\frac{2}{6}\)=\(\frac{10}{30}\)<\(\frac{8}{20}\)<\(\frac{5}{12}\)
Do \(\dfrac{{ - 11}}{8} < 0\) và \(\dfrac{1}{{24}} > 0\) nên \(\dfrac{{ - 11}}{8} < \dfrac{1}{{24}}\)
-11/8<1/24
3/20<6/15
Câu 1 : >
Câu 2 : <