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ket qua la 2.711779115

cậu ấn vào câu hỏi tương tự là nó hiển thị ra các câu khác có câu trả lời đấy

Ta có \(\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{19}=\left(\frac{3}{10}-\frac{6}{20}-\frac{4}{15}-\frac{1}{20}\right).\frac{5}{19}=-\left(\frac{4}{15}+\frac{1}{20}\right).\frac{5}{19}\)

\(=-\frac{1}{5}\left(\frac{4}{3}+\frac{1}{4}\right).\frac{5}{19}=-\left(\frac{4}{3}+\frac{1}{4}\right).\frac{1}{19}=-\frac{19}{12}.\frac{1}{19}=-\frac{1}{12}\)

Lại có \(\left(\frac{1}{14}+\frac{1}{7}-\frac{3}{35}\right).\frac{-4}{3}=\left(\frac{1}{14}+\frac{1}{7}-\frac{5}{35}+\frac{2}{35}\right).\frac{-4}{3}=\left(\frac{1}{14}+\frac{2}{35}\right).\frac{-4}{3}\)

\(=\frac{1}{7}\left(\frac{1}{2}+\frac{2}{5}\right).\frac{-4}{3}=\left(\frac{1}{2}+\frac{2}{5}\right).\frac{-4}{21}=\frac{7}{10}.\frac{-4}{21}=\frac{-2}{15}\)

Khi đó \(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{19}}{\left(\frac{1}{14}+\frac{1}{7}-\frac{3}{35}\right).\frac{-4}{3}}=\frac{\frac{1}{12}}{-\frac{2}{15}}=-\frac{5}{8}\)

Làm lại : 

\(\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\left(-\frac{4}{3}\right)=\left(\frac{1}{14}+\frac{1}{7}-\frac{5}{35}+\frac{2}{35}\right)\left(-\frac{4}{3}\right)=\left(\frac{1}{14}+\frac{2}{35}\right)\left(-\frac{4}{3}\right)\)

\(=\frac{1}{7}\left(\frac{1}{2}+\frac{2}{5}\right).\frac{-4}{3}=\frac{-4}{21}.\frac{9}{10}=\frac{-6}{35}\)

Khi đó A = \(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{19}}{\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\frac{-4}{3}}=\frac{-\frac{1}{12}}{-\frac{6}{35}}=\frac{35}{72}\)

ta có :

\(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{19}}{\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\frac{-4}{3}}=\frac{\frac{1}{5}\left(\frac{3}{2}-\frac{2}{3}-\frac{7}{4}\right).\frac{5}{19}}{\frac{1}{7}\left(\frac{1}{2}+1+\frac{3}{5}\right).\frac{-4}{3}}=\frac{\frac{1}{19}\left(-\frac{2}{3}-\frac{1}{4}\right)}{-\frac{3}{21}\left(\frac{3}{2}+\frac{3}{5}\right)}=\frac{\frac{1}{19}.\frac{-11}{12}}{-\frac{3}{21}.\frac{21}{10}}\)

\(=\frac{\frac{1}{19}.\frac{-11}{12}}{-\frac{3}{10}}=\frac{11}{19.12}.\frac{10}{3}=\frac{55}{342}\)

a ) \(\frac{7}{19}.\frac{8}{11}+\frac{3}{11}.\frac{7}{19}+\frac{-12}{19}\)

\(=\frac{7}{19}.\left(\frac{8}{11}+\frac{3}{11}\right)+\frac{-12}{19}\)

\(=\frac{7}{19}.\frac{11}{11}+\frac{-12}{19}\)

\(=\frac{7}{19}.1+\frac{-12}{19}\)

\(=\frac{7}{19}+\frac{-12}{19}\)

\(=\frac{7+\left(-12\right)}{19}\)

\(=-\frac{5}{19}\)

b ) \(\frac{-7}{25}.\frac{39}{-14}.\frac{50}{78}=\frac{-7.39.50}{25.-14.78}=\frac{-1.1.2}{1.-2.2}=\frac{-2}{-4}=\frac{1}{2}\)

c ) \(\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)

\(=\frac{5}{24}:\frac{5}{6}+\frac{1}{2}\)

\(=\frac{5}{24}.\frac{6}{5}+\frac{1}{2}\)

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

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

a)\(\frac{7}{19}.\frac{8}{11}+\frac{3}{11}.\frac{7}{19}+\frac{-12}{19}=\frac{7}{19}.\frac{8}{11}+\frac{3}{11}.\frac{7}{19}+\frac{7}{19}.\frac{-12}{7}=\frac{7}{19}.\left(\frac{8}{11}+\frac{3}{11}+-\frac{12}{7}\right)=\frac{7}{19}.\left(\frac{-5}{7}\right)=-\frac{5}{19}\)

b)\(\frac{-7}{25}.\frac{39}{-14}.\frac{50}{78}=\frac{\left(-7\right).39.50}{25.\left(-14\right).78}=\frac{\left(-7\right).3.13.2.5.5}{5.5.\left(-7\right).2.2.13.3}=\frac{1}{2}\)

c)\(\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}=\frac{5}{24}:\frac{5}{6}+\frac{1}{2}=\frac{2}{7}+\frac{1}{2}=\frac{11}{14}\)

hoc kim dong ak

\(\frac{-3}{5}.\left(\frac{5}{7}+\frac{3}{7}+\frac{6}{7}\right)\)

=\(\frac{-3}{5}.\)\(\frac{14}{7}\)

=\(-\frac{3}{5}.2\)

=-6/5

B=47/41.[12.(1+1/19-1/37-1/53)/3.(1+1/19-1/37-1/53):4.(1+1/17+1/19+1/2006)/5.(1+1/17+1/19+1/2006)].123/235

=47/41.[4:4/5].123/235

=47/41.5.123/235=3

C=63.10101.37-37.10101.63/1+2+3+...+2006

=0/1+2+3+...+2006=0

CẬU XEM LẠI CHO MÌNH NHA!

\(\frac{636363.37-373737.63}{1+2+3+...+2006}=\frac{63.10101.37-37.10101.63}{1+2+3+...+2006}=\frac{0}{1+2+3+...+2006}=0\)

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Mình nghĩ đề thế này mới tính hợp lí được

2 ) B = \(1\frac{6}{41}.\left(\frac{12+\frac{12}{19}-\frac{12}{37}-\frac{12}{53}}{3+\frac{3}{19}-\frac{3}{37}-\frac{3}{53}}:\frac{4+\frac{4}{17}+\frac{4}{19}+\frac{4}{2006}}{5+\frac{5}{17}+\frac{5}{19}+\frac{5}{2006}}\right).\frac{124242423}{237373735}\)

B = 47/41 . ( 12/3 : 4/5 ) . 123/235

B = 47/41 . ( 4 : 4/5 ) . 123/235

B = 47/41 . 5 . 123/235

B = \(\frac{47.5.123}{41.235}\)

B = 3

1 ) A = \(\frac{636363.37-373737.63}{1+2+3+...+2006}\)

A = \(\frac{63.10101.37-37.10101.63}{1+2+3+...+2006}\)

A = \(\frac{0}{1+2+3+...+2006}\)

A = 0

a. \(\frac{1}{3}.\frac{4}{5}+\frac{1}{3}.\frac{6}{5}-\)

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

\(=\frac{1}{3}.2-\frac{5}{3}\)

\(=\frac{2}{3}-\frac{5}{3}\)

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

c. \(\frac{6}{7}.\frac{10}{9}+\frac{1}{7}.\frac{10}{9}-\frac{8}{9}\)

\(=\frac{10}{9}\left(\frac{6}{7}+\frac{1}{7}\right)-\frac{8}{9}\)

\(=\frac{10}{9}.1-\frac{9}{8}\)

\(=\frac{10}{9}-\frac{9}{8}\)

\(=-\frac{1}{72}\)

\(b\).\(\frac{4}{19}.\frac{-3}{7}+\frac{-3}{7}.\frac{15}{19}+\frac{5}{7}\)

\(=\frac{-3}{7}\left(\frac{4}{19}+\frac{15}{19}\right)+\frac{5}{7}\)

\(=\frac{-3}{7}+\frac{5}{7}\)

\(=\frac{2}{7}\)