Question

quy dong mau 2 phan so3/12 va -5/20

Answer 1

Cách 1 :Ta thấy \(\frac{3}{12}\)là phân số dương

Mà \(-\frac{5}{20}\)là phân số âm

Do đó \(\frac{3}{12}>\frac{-5}{20}\)

Cách 2 : Ta thấy BCNN(12;20)=60

Khi đó \(\frac{3}{12}=\frac{3.5}{12.5}=\frac{15}{60}=\frac{1}{4}\)

\(\frac{-5}{20}=\frac{-5.3}{20.3}=\frac{-15}{60}=-\frac{1}{4}\)

Answer 2

\(\frac{3}{12}\&\frac{-5}{20}\)

\(\frac{3}{12}=\frac{3\cdot20}{12\cdot20}=\frac{60}{240}\)

\(\frac{-5}{20}=\frac{-5\cdot12}{20\cdot12}=\frac{-60}{240}\)

Answer 3

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Answer 4

       \(12=2^2.3\)

      \(20=2^2.5\)

\(\Rightarrow\)BCNN(12;20)=\(2^2.3.5\)

                               =60

\(\frac{3}{12}=\frac{3.5}{12.5}=\frac{15}{60}\)

\(\frac{-5}{20}=\frac{-5.3}{20.3}=\frac{-15}{60}\)

tk nha