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a \(\frac{4}{18}+\frac{5}{13}+\frac{7}{9}+\frac{21}{13}\)

= \(\left(\frac{4}{18}+\frac{7}{9}\right)+\left(\frac{5}{13}+\frac{21}{13}\right)\)

= \(1+2\)

= \(3\)

b \(\frac{4}{3}-\frac{2}{7}-\frac{5}{7}+\frac{2}{3}\)

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

= \(\frac{2}{3}-1\)

= \(-\frac{1}{3}\)

Kết quả của bài 1/5+1/10+1/20+1/40+1/80+1/160 là gì

Ta có: \(1\frac{4}{5}+2\frac{5}{7}+3\frac{4}{5}+4\frac{5}{7}\)

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

\(=\left(\frac{9}{5}+\frac{19}{5}\right)+\left(\frac{19}{7}+\frac{33}{7}\right)\)

\(=\frac{28}{5}+\frac{52}{7}=13\frac{1}{35}\)

= ( \(1\frac{4}{5}\)+ \(3\frac{4}{5}\)) + (  \(2\frac{5}{7}\)+  \(4\frac{5}{7}\))         

=        \(4\frac{4}{5}\)           +       \(6\frac{5}{7}\)

=           \(\frac{24}{5}\)         +        \(\frac{47}{7}\)

=  ...... ( tính nốt nhé )

=(1+3)×4/5+(2+4)×5/7

=4×4/5+6×5/7

=16/5+30/7

=16×6/7

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

\(=6\frac{5}{7}-1\frac{3}{4}-2\frac{5}{7}\)

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

\(=4-1\frac{3}{4}\)

\(=2\frac{1}{4}\)

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

\(=6\frac{5}{7}-1\frac{3}{4}-2\frac{5}{7}\)

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

\(=4-\frac{7}{4}\)

\(=\frac{16}{4}-\frac{7}{4}\)

\(=\frac{9}{4}\)

=   \(6\frac{5}{7}-1\frac{3}{4}-2\frac{5}{7}=6\frac{5}{7}-2\frac{5}{7}\)\(-1\frac{3}{4}\)=   \(4-1\frac{3}{4}\)=\(\frac{9}{4}\)

47/7 - (7/4 + 19/7) =47/7 -125/28 =gomen =tao xin lỗi chịu rùi = <3

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

\(=6\frac{5}{7}-1\frac{3}{4}-2\frac{5}{7}\)

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

\(=\left(\frac{47}{7}-\frac{19}{7}\right)-\frac{7}{4}\)

\(=\frac{28}{7}-\frac{7}{4}\)

\(=4-\frac{7}{4}\)

\(=\frac{16}{4}-\frac{7}{4}\)

\(=\frac{9}{4}\)

\(\frac{5}{16}+\frac{5}{7}+0,4+\frac{1}{6}-\frac{4}{35}\)

= \(\frac{5}{16}+\frac{25}{35}+\frac{2}{5}+\frac{1}{6}-\frac{4}{35}\)

= \(\frac{5}{16}+\frac{2}{5}+\frac{1}{6}+\frac{25}{35}-\frac{4}{35}\)

= \(\frac{5}{16}+\frac{2}{5}+\frac{1}{6}+\frac{2}{3}\)

= \(\frac{5}{16}+\frac{2}{5}+\frac{5}{6}\)

= \(\frac{5}{16}+\frac{37}{30}\)

= \(\frac{371}{240}\)