a,     (\(\dfrac{9}{10}\) - \(\dfrac{15}{16}\)) \(\times\) ( \(\dfrac{5}{12}\) - \(\dfrac{11}{15}\) - \(\dfrac{7}{20}\))

=  (\(\dfrac{72}{80}\) - \(\dfrac{75}{80}\))  \(\times\) (\(\)\(\dfrac{25}{60}\) - \(\dfrac{44}{60}\)  - \(\dfrac{21}{60}\))

= - \(\dfrac{3}{80}\)  \(\times\) (- \(\dfrac{2}{3}\))

= \(\dfrac{1}{40}\) 

b, (-1)³ + (- \(\dfrac{2}{3}\))² : 2\(\dfrac{2}{3}\) + \(\dfrac{5}{6}\)

=  -1³ +   \(\dfrac{4}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{5}{6}\)

= -1 + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{3}{8}\) + \(\dfrac{5}{6}\)

= -1 + \(\dfrac{1}{6}\) + \(\dfrac{5}{6}\)
= -1 + 1

= 0

\(-\frac{15}{12}x+\frac{3}{7}=\frac{6}{5}x-\frac{1}{2}\)

\(\frac{15}{12}x+\frac{6}{5}x=\frac{1}{2}+\frac{3}{7}\)

\(\frac{75}{60}x+\frac{72}{60}x=\frac{7}{14}+\frac{6}{14}\)

\(\frac{147}{60}x=\frac{13}{14}\)

\(x=\frac{13}{14}\div\frac{147}{60}\)

\(x=\frac{13}{14}\times\frac{60}{147}\)

\(x=\frac{130}{343}\)

hanh lên mai làm rùi mấy chế oi

-15/12. x+3/7=6/5.x-1/2

=> -15/12  . x +3/7+1/2 = 6/5  .x

=> -15/12   .x + 13/14= 6/5  .x 

=>  49/20 .x = 13/14 => x= 130/343

a: \(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{5}=2\\x+\dfrac{1}{5}=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{9}{5}\\x=-\dfrac{11}{5}\end{matrix}\right.\)

\(a,\left|x+\dfrac{1}{5}\right|-4=-2\\ \left|x+\dfrac{1}{5}\right|=\left(-2\right)+4\\ \left|x+\dfrac{1}{5}\right|=2\Rightarrow x+\dfrac{1}{5}=2\)

hoặc \(x+\dfrac{1}{5}=-2\)

Với \(x+\dfrac{1}{5}=2\Rightarrow x=2-\dfrac{1}{5}\)hay \(x=\dfrac{9}{5}\)

Với \(x+\dfrac{1}{5}=-2\Rightarrow x=-2-\dfrac{1}{5}\)hay \(x=-\dfrac{11}{5}\)

Thông cảm . bt làm mỗi câu a

Bài 1:

a) \(=\dfrac{8}{15}\left(\dfrac{7}{13}+\dfrac{6}{13}\right)=\dfrac{8}{15}.1=\dfrac{8}{15}\)

b) \(=\dfrac{3.3-7-2.4}{12}=-\dfrac{6}{12}=-\dfrac{1}{2}\)

Bài 2:

 \(\dfrac{x}{2,7}=-\dfrac{2}{3,6}\Rightarrow x=\dfrac{\left(-2\right).2,7}{3,6}\Rightarrow x=-\dfrac{3}{2}\)

Bài 3:

\(\dfrac{x}{2}=\dfrac{y}{5}=\dfrac{x+y}{2+5}=-\dfrac{21}{7}=-3\)

\(\Rightarrow\left\{{}\begin{matrix}x=\left(-3\right).2=-6\\y=\left(-3\right).5=-10\end{matrix}\right.\)

\(\frac{5}{6} + \left [ \frac{2}{3}x - \left ( \frac{-7}{12} \right ) \right ]= \frac{1}{2}\)

\(\frac{2}{3}x + \frac{7}{12}= -\frac{1}{3}\)

\(\frac{2}{3}x = - \frac{1}{3} - \frac{7}{12}\)

\(\frac{2}{3}x= -\frac{11}{12}\)

\(x= - \frac{11}{8}\)

Vậy \(x= - \frac{11}{8}\)

b) \(\frac{x}{15} + 1,2= \frac{1}{3}\)

\(\frac{x}{15}= \frac{1}{3} - 1,2\)

\(\frac{x}{15}=- \frac{13}{15}\)

x = - 13

Vậy x = - 13

câu c pn coi lại đề nhé

d) 3 + \(\left | x - 1,34 \right |\) = 5

\(\left | x - 1,34 \right |\) = 5 - 3

\(\left | x - 1,34 \right |\) = 2

\(\Leftrightarrow \begin{bmatrix} x - 1,34 = 2 & & \\ x - 1,34= 2 & & \end{bmatrix}\) \(\Leftrightarrow \begin{bmatrix} x= 3,34 & & \\ x = - 0,66 & & \end{bmatrix}\)

(bỏ dấu ngoặc bên phải nha pn)

Vậy x = 3,34; x = - 0,66

câu e pn lm tương tự

thanks pn nha

0,0140...

Noob ơi, bạn phải đưa vào máy tính ý solve cái là ra x luôn, chỉ tội là đợi hơi lâu

a, 4.(18 - 5x) - 12(3x - 7) = 15(2x - 16) - 6(x + 14) 

=> 72 - 20x - 36x + 84 = 30x - 240 - 6x - 84

=> (72 + 84) + (-20x - 36x) = (30x - 6x) + (-240 - 84) 

=> 156 -  56x = 24x - 324 

=>  24x + 56x = 324 + 156 

=> 80x = 480 

=> x = 480 : 80 =  6 

Vậy x = 6 

\(\dfrac{3}{7}+\dfrac{1}{2}=\dfrac{-15}{12}x+\dfrac{6}{5}x\)

\(\Leftrightarrow\)\(\dfrac{-15.5+12.6}{60}x=\dfrac{3.2+1.7}{14}\)

\(\Leftrightarrow\)\(\dfrac{-3}{60}x=\dfrac{13}{14}\)

\(\Leftrightarrow\)\(\dfrac{-1}{20}x=\dfrac{13}{14}\)

\(\Leftrightarrow\)x=-\(\dfrac{13}{14}:\dfrac{1}{20}=-\dfrac{13.20}{14}=-\dfrac{130}{7}\)

3(12+x)=7(x-4)

\(\Leftrightarrow\)36+3x=7x-28

\(\Leftrightarrow\)7x-3x=36+28

\(\Leftrightarrow\)4x=64

\(\Leftrightarrow\)x=16