1, Ta có :

     \(x+\frac{3}{5}=\frac{4}{7}\div\frac{8}{21}\)

    \(x+\frac{3}{5}=\frac{4}{7}\times\frac{21}{8}\)

    \(x+\frac{3}{5}=\frac{3}{2}\)

    \(x=\frac{3}{2}-\frac{3}{5}\)

    \(x=\frac{15}{10}-\frac{6}{10}\)

    \(x=\frac{9}{10}\)

Vậy x = \(\frac{9}{10}\)

2, Ta có :

    \(\frac{2}{3}+\frac{3}{4}\div x=-\frac{1}{6}\)

    \(\frac{3}{4}\div x=-\frac{1}{6}-\frac{2}{3}\)

    \(\frac{3}{4}\div x=-\frac{1}{6}-\frac{4}{6}\)

    \(\frac{3}{4}\div x=-\frac{5}{6}\)

    \(x=\frac{3}{4}\div\left(-\frac{5}{6}\right)\)

    \(x=\frac{3}{4}\times\left(-\frac{6}{5}\right)\)

    \(x=-\frac{9}{10}\)

Vậy x = \(-\frac{9}{10}\)

thanks bạn nha

chúc bạn ngày mai thi tốt nha

Bài này bạn làm hả .

Chúc bạn thi tốt nha .

Mà bạn đừng đăng linh tinh nữa , cẩn thận các bạn khác báo cáo đấy . ( Mình chỉ nhắc vậy thôi nha chứ không có ý gì hết ).

Giải :

1. ( 1999 + 313 ) – 1999 = 1999 – 1999 + 313 = 313

( 1435 + 213 ) – 13 = 1435 + ( 213 – 13 ) = 1435 + 200 = 1635

1. 2034 – ( 34 + 1560 ) = ( 2034 – 34 ) – 1560 = 2000 – 1560 = 440

1972 – ( 364 + 972 ) = 1972 – 972 – 368 = 1000 – 368 = 632

      c.    364 – ( 364 – 111 ) = 364 – 364 + 111 = 111

             249 – ( 75-51 ) = ( 249 + 51 ) – 75 = 300 – 75 = 225

Make the sentenes with the given words:

1. Our classmates/ be/ to/ beaches/ Nha trang/ many/ times.

-> Our classmates have been to many beaches Trang many times

2. Instead/ keys, we/ will/ have/ special/ cards/ start/ the/ engine/ the car.

-> Instead of using keys, we will have special cards to start the engine of the car

               \(\left(75\%+\frac{1}{2}\right)\text{ : }\left|-1\frac{1}{2}\right|-\frac{5}{27}\cdot1,8\cdot2012^0\)

\(=\left(\frac{3}{4}+\frac{1}{2}\right):\left|-\frac{3}{2}\right|-\frac{5}{27}\cdot\frac{9}{5}\)

\(=\frac{5}{4}\text{ : }\frac{3}{2}-\frac{1}{3}\)

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

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

\(\left(75\%+\frac{1}{2}\right)-\left|-1\frac{1}{2}\right|-\frac{5}{27}\cdot1,8\cdot2012^0\)

\(=\left(\frac{75}{100}+\frac{1}{2}\right)-\left|-\frac{3}{2}\right|-\frac{5}{27}\cdot\frac{9}{5}\cdot1\)

\(=\left(\frac{3}{4}+\frac{1}{2}\right)-\frac{3}{2}-\frac{5}{27}\cdot\frac{9}{5}\)

\(=\left(\frac{3}{4}+\frac{2}{4}\right)-\frac{3}{2}\cdot\frac{1}{3}\)

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

Ez mà :)))

\(\frac{7}{5}.\left(\frac{-11}{8}+\frac{-9}{8}\right)+\frac{9}{2}\)

\(\frac{7}{5}.\left(\frac{-5}{2}\right)+\frac{9}{2}\)

\(\frac{-7}{2}+\frac{9}{2}\)

=1

\(\frac{7}{5}.\frac{-11}{8}+\frac{7}{5}.\frac{9}{-8}+4\frac{1}{2}\)

=\(\frac{7}{5}.\left(\frac{-11}{8}+\frac{-9}{8}\right)+\frac{9}{2}\)

=\(\frac{7}{5}.\frac{-20}{8}+\frac{9}{2}\)

=\(\frac{-140}{40}+\frac{9}{2}\)

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

= -10 nhá

kết quả m chưa ghi