-5/12 và7/-14
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- \(\dfrac{5}{12}\) < 0 < \(\dfrac{7}{14}\)
Vậy - \(\dfrac{5}{12}\) < \(\dfrac{7}{14}\)
\(\frac{-5}{8}\)và \(\frac{7}{-12}\)
Ta có: \(\frac{7}{-12}=\frac{-7}{12}\)
- Tìm BCNN(8, 12)
8 = 23
12 = 22 . 3
\(\rightarrow\)BCNN(8, 12) = 23 . 3 = 24
- Tìm thừa số phụ tương ứng:
24 : 8 = 3
24 : 12 = 2
- Nhân cả tử và mẫu của phân số cho thừa số phụ tương ứng:
\(\frac{-5}{8}=\frac{-5.3}{8.3}=\frac{-15}{24}\)
\(\frac{-7}{12}=\frac{-7.2}{12.2}=\frac{-14}{24}\)
Vì \(\frac{-15}{24}< \frac{-14}{24}\Rightarrow\frac{-5}{8}< \frac{7}{-12}\)
#Hok tốt
`a,MSC:30`
`1/2=(1xx15)/(2xx15)=15/30`
`2/3=(2xx10)/(3xx10)= 20/30`
`3/5=(3xx6)/(5xx6)=18/30`
`b,MSC:12`
`2/3=(2xx4)/(3xx4)=8/12`
`3/4=(3xx3)/(4xx3)=9/12`
`7/12` giữ nguyên
\(a,\dfrac{1}{4},\dfrac{5}{6}và\dfrac{7}{12}\)
\(\dfrac{1}{4}=\dfrac{1\times3}{4\times3}=\dfrac{3}{12};\dfrac{5}{6}=\dfrac{5\times2}{6\times2}=\dfrac{10}{12};\dfrac{7}{12}\)
\(b,\dfrac{1}{9},\dfrac{3}{5},\dfrac{11}{45}\)
\(\dfrac{1}{9}=\dfrac{1\times5}{9\times5}=\dfrac{5}{45};\dfrac{3}{5}=\dfrac{3\times9}{5\times9}=\dfrac{27}{45};\dfrac{11}{45}\)
\(\dfrac{3\dfrac{1}{3}+\dfrac{1}{5}+2\dfrac{7}{15}}{\left(\dfrac{3}{10}+\dfrac{1}{4}+\dfrac{7}{20}\right).\dfrac{5}{6}}=\dfrac{\dfrac{10}{3}+\dfrac{1}{5}+\dfrac{37}{15}}{\left(\dfrac{6}{20}+\dfrac{5}{20}+\dfrac{7}{20}\right).\dfrac{5}{6}}\)
\(=\dfrac{\dfrac{50}{15}+\dfrac{3}{15}+\dfrac{37}{15}}{\dfrac{18}{20}.\dfrac{5}{6}}=\dfrac{6}{\dfrac{3}{4}}=\dfrac{6.4}{3}=8\)
\(\dfrac{3}{25}\) và \(\dfrac{7}{10}\)
\(\dfrac{3}{25}\) = \(\dfrac{3\times2}{25\times2}\) = \(\dfrac{6}{50}\)
\(\dfrac{7}{10}\) = \(\dfrac{7\times5}{10\times5}\) = \(\dfrac{35}{50}\)
\(\dfrac{6}{50}\) < \(\dfrac{35}{50}\)
Vậy \(\dfrac{3}{25}\) < \(\dfrac{7}{10}\)
\(\dfrac{-5}{12}\) và \(\dfrac{-7}{14}\)
\(\dfrac{-5}{12}=\dfrac{-70}{168};\dfrac{-7}{14}=\dfrac{-84}{168}\)
Vậy \(\dfrac{-5}{12}\) lớn hơn
- \(\dfrac{5}{12}\) = - \(\dfrac{5\times7}{12\times7}\) = - \(\dfrac{35}{84}\)
\(\dfrac{7}{-14}\) = - \(\dfrac{7\times5}{14\times5}\) = - \(\dfrac{35}{70}\)
Vì \(\dfrac{35}{84}\) < \(\dfrac{35}{70}\)
Nên - \(\dfrac{35}{84}\) > - \(\dfrac{35}{70}\)
Vậy - \(\dfrac{5}{12}\) > \(\dfrac{7}{-14}\)