a) -3/20 + -4/20 = -7/20

b) 1/20 - 8/20 = -7/20 

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ơ sao sai

MÌNH KO ẤN SAI NHÉ

1. a, \(\frac{-4}{15}=\left(\frac{-1}{15}+\frac{-3}{15}\right)=\left(\frac{-2}{15}+\frac{-2}{15}\right)=\left(\frac{-0}{15}+\frac{4}{15}\right)\)

b, \(\frac{-4}{15}=\left(\frac{4}{15}-\frac{8}{15}\right)=\left(\frac{3}{15}-\frac{7}{15}\right)=\left(\frac{5}{15}-\frac{9}{15}\right)\)

2 . \(\frac{-7}{12}=\left(\frac{-1}{12}+\frac{-1}{2}\right)=\left(\frac{-1}{6}+\frac{-5}{12}\right)=\left(\frac{-1}{4}+\frac{-1}{3}\right)\)

b, \(\frac{-7}{12}=\left(\frac{4}{12}-\frac{11}{12}\right)=\left(\frac{1}{12}-\frac{8}{12}\right)=\left(\frac{3}{12}-\frac{10}{12}\right)\)

a)
\(\frac{-7}{20}=\frac{-7}{3}.\frac{3}{20}\)

b)

\(\frac{-7}{20}=\frac{-7}{3}:\frac{20}{3}\)

c)

\(\frac{-2}{5}+\frac{1}{20}\)

a) -7/20= (-1/4)+ (-1/10)= (-3/20)+ (-1/5)= (-1/20)+(-3/10)

b)-7/20= 1/20 -2/5=1/10 -9/20=3/20 -1/2

Bài này dễ mà QAQ

Ta có : \(\frac{-7}{20}=\frac{\left(-1\right)+\left(-6\right)}{20}=\frac{\left(-2\right)+\left(-5\right)}{20}=\frac{\left(-3\right)+\left(-4\right)}{20}\)

Do đó \(\frac{-7}{20}=\frac{-1}{20}+\frac{-6}{20}=\frac{-1}{20}+\frac{-3}{10}\)

\(\frac{-7}{20}=\frac{-2}{20}+\frac{-5}{20}=\frac{-1}{10}+\frac{-1}{4}\)

\(\frac{-7}{20}=\frac{-3}{20}+\frac{-4}{20}=\frac{-3}{20}+\frac{-2}{10}\)

b) \(\frac{-7}{20}=\frac{1-8}{20}=\frac{2-9}{20}=\frac{3-10}{20}\)

Do đó \(\frac{-7}{20}=\frac{1}{20}-\frac{8}{20}=\frac{1}{20}-\frac{4}{10}\)

\(\frac{-7}{20}=\frac{2}{20}-\frac{9}{20}=\frac{1}{10}-\frac{9}{20}\)

\(\frac{-7}{20}=\frac{3}{20}-\frac{10}{20}=\frac{3}{20}-\frac{1}{2}\)

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-2/10=1/5

4/10=2/5

a) \(-\frac{15}{32}=-\frac{1}{4}+\left(-\frac{7}{32}\right)\)

b) \(-\frac{15}{32}=\frac{1}{32}-\frac{1}{2}\)

\(a;\frac{-5}{16}=\frac{-1}{8}+\frac{-3}{16}\)

\(b;\frac{-5}{16}=\frac{1}{16}-\frac{3}{8}\)