a: Dấu hiệu là thời gian giải bài

Số các giá trị là 10

b: 

Mốt là 7 và 8

c: Phần lớn làm xong trong 7 hoặc 8 phút

1,-(4+7)=(-4-7)

2,-(12-25)=(-12+25)

3,-(-8+7)=(8-7)

4,+(-15-4)=(-15-4)

5,+(23-12)=(23-12).

bằng nhau hết nha bạn

bạn ấy ko biết mới đăng lên giỏi thì bạn làm đi Đỗ Hoàng Anh

\(\frac{12+\frac{12}{7}+\frac{12}{85}}{4+\frac{4}{7}+\frac{4}{85}}=\frac{12\left(1+\frac{1}{7}+\frac{1}{85}\right)}{4\left(1+\frac{1}{7}+\frac{1}{85}\right)}=\frac{12}{4}=3\)

(12+12/7+12/85):(4+4/7+4/85)

=12(1+1/7+1/85):4(1+1/7+1/85

=3

\(=\dfrac{3.4-\dfrac{3.4}{4}-\dfrac{3.4}{289}-\dfrac{3.4}{85}}{4-\dfrac{4}{7}-\dfrac{4}{289}-\dfrac{4}{85}}=\dfrac{3.\left(4-\dfrac{4}{7}-\dfrac{4}{289}-\dfrac{4}{85}\right)}{1.\left(4-\dfrac{4}{7}-\dfrac{4}{289}-\dfrac{4}{85}\right)}=\dfrac{3}{1}=3\)

=3

=3

b nha bạn 

b

\(\frac{7}{9}\)

(5/12+7/12) nhân 4/7=4/7

hok tốt

\(\frac{4}{7}.\frac{5}{12}+\frac{4}{7}.\frac{7}{12}+\frac{4}{7}\)

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

\(=\frac{4}{7}\left(\frac{12}{12}+1\right)\)

\(=\frac{4}{7}.2\)

\(=\frac{8}{7}\)

\(\frac{4}{7}\times\frac{5}{12}+\frac{4}{7}\times\frac{7}{12}+\frac{4}{7}\)

\(=\frac{4}{7}\times\frac{5}{12}+\frac{4}{7}\times\frac{7}{12}+\frac{4}{7}\times1\)

\(=\frac{4}{7}\times\left(\frac{5}{12}+\frac{7}{12}+1\right)\)

\(=\frac{4}{7}\times\left(\frac{12}{12}+1\right)\)

\(=\frac{4}{7}\times\left(1+1\right)\)

\(=\frac{4}{7}\times2=\frac{4}{7}\times\frac{2}{1}=\frac{8}{7}\)

(đúng thì k, sai thì thôi)

\(1)\)\(-\dfrac{10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

\(=\dfrac{10}{11}\left(-\dfrac{8}{9}+\dfrac{7}{18}\right)\)

\(=\dfrac{10}{11}\left(\dfrac{-16}{18}+\dfrac{7}{18}\right)\)

\(=\dfrac{10}{11}.\left(-\dfrac{1}{2}\right)=-\dfrac{5}{11}\)

\(2)\)\(\dfrac{12}{25}.\dfrac{23}{7}-\dfrac{12}{7}.\dfrac{13}{25}\)

\(=\dfrac{12}{7}.\dfrac{23}{25}-\dfrac{12}{7}.\dfrac{13}{25}\)

\(=\dfrac{12}{7}.\left(\dfrac{23}{25}-\dfrac{13}{25}\right)\)

\(=\dfrac{12}{7}.\dfrac{2}{5}=\dfrac{24}{35}\)

\(3)\)\(\dfrac{3}{7}.\dfrac{16}{15}-\dfrac{2}{15}.\dfrac{-3}{7}\)

\(=\dfrac{3}{7}.\dfrac{16}{15}-\dfrac{3}{7}.\dfrac{-2}{15}\)

\(=\dfrac{3}{7}.\left(\dfrac{16}{15}+\dfrac{2}{15}\right)\)

\(=\dfrac{3}{7}.\dfrac{18}{15}=\dfrac{18}{35}\)

\(4)\)\(-\dfrac{4}{13}.\dfrac{5}{17}+\dfrac{-12}{13}.\dfrac{4}{17}\)

\(=-\dfrac{4}{13}.\dfrac{5}{17}+\dfrac{-4}{13}.\dfrac{12}{17}\)

\(=-\dfrac{4}{13}.\left(\dfrac{5}{17}+\dfrac{12}{17}\right)\)

\(=-\dfrac{4}{13}.\dfrac{17}{17}=-\dfrac{4}{13}\)

`#040911`

`1)`

`-10/11 * 8/9 + 7/18 . 10/11`

`= 10/11 * (-8/9 + 7/18)`

`= 10/11 * (-1/2)`

`= -5/11`

`2)`

`12/25 * 23/7 - 12/7 *13/25`

`= 12/7 * 23/25 - 12/7 * 13/25`

`= 12/7 * (23/25 - 13/25)`

`= 12/7 * 2/5`

`= 24/35`

`3)`

`3/7 * 16/15 - 2/15 * (-3)/7`

`= 3/7 * (16/15 + 2/15)`

`= 3/7 * 6/5`

`= 18/35`

`4)`

`-4/13 * 5/17 + (-12)/13 * 4/17`

`= -4/17 * 5/13 + (-12)/13 * 4/17`

`= 4/17 * (-5/13 - 12/13)`

`= 4/17 * (-17)/13`

`= -4/13`

giúp mình với

a)\(=\dfrac{4}{7}+\dfrac{3}{7}\times\dfrac{14}{5}=\dfrac{4}{7}+\dfrac{6}{5}=\dfrac{20}{35}+\dfrac{42}{35}=\dfrac{62}{35}\)

b)\(=\dfrac{7}{12}-\dfrac{1}{12}\times\dfrac{4}{2}\times\dfrac{27}{16}=\dfrac{7}{12}-\dfrac{3}{16}=\dfrac{19}{48}\)

A  =\(\frac{2}{5}\times\frac{4}{7}+\frac{3}{5}\times\frac{4}{7}\)  B = \(\frac{17}{13}\times\frac{12}{17}-\frac{4}{13}\times\frac{12}{17}\)   C = \(\frac{9}{14}:\frac{6}{7}+\frac{5}{14}:\frac{6}{7}\)  D =\(\frac{9}{12}:\frac{7}{9}\times\frac{12}{19}\)

=  \(\frac{4}{7}\times\left(\frac{2}{5}+\frac{3}{5}\right)\)              =\(\left(\frac{17}{13}-\frac{4}{13}\right)\times\frac{12}{17}\)                = \((\frac{9}{14}+\frac{5}{14}):\frac{6}{7}\)         = \(\frac{9}{12}\times\frac{9}{7}\times\frac{12}{19}\)

=\(\frac{4}{7}\times1\)                                     = \(1\times\frac{12}{17}\)                                       = \(1:\frac{6}{7}\)                               = \(\frac{9\times9\times12}{12\times7\times19}\)

=\(\frac{4}{7}\)                                              =  \(\frac{12}{17}\)                                                =\(\frac{7}{6}\)                                    = \(\frac{9\times9}{7\times19}=\frac{81}{133}\)

   -