`-3/5xx9/14-3/5xx5/14+3/5`

`=(-3/5+3/5)xx(9/14+5/14)xx3/5`

`=0xx14xx3/5`

`=0xx1xx3/5`

`=0xx3/5`

`=0`

`@Nae`

\(-\dfrac{3}{5}\times\dfrac{9}{14}-\dfrac{3}{5}\times\dfrac{5}{14}+\dfrac{3}{5}\)

\(=\dfrac{3}{5}\times\left(-\dfrac{9}{14}-\dfrac{5}{14}+1\right)\)

\(=\dfrac{3}{5}\times\left(\dfrac{-9-5+14}{14}\right)\)

\(=\dfrac{3}{5}\times\dfrac{0}{14}\)

\(=0\)

a: \(=\dfrac{2}{5}+\dfrac{3}{5}\cdot\dfrac{10}{3}\cdot\dfrac{1}{2}=\dfrac{2}{5}+\dfrac{10}{5}\cdot\dfrac{1}{2}=\dfrac{2}{5}+1=\dfrac{7}{5}\)

a: \(=3\cdot\dfrac{6+14-9}{42}\cdot\dfrac{14}{11}\)

\(=3\cdot\dfrac{11}{42}\cdot\dfrac{14}{11}=1\)

b: \(=\dfrac{19}{5}\cdot\dfrac{11}{10}+\dfrac{9}{5}\cdot\dfrac{7}{3}\)

\(=\dfrac{209}{50}+\dfrac{63}{15}=4.18+4.2=8,38\)

|7 - \(\dfrac{3}{4}\)\(x\)| - \(\dfrac{3}{2}\) = \(\dfrac{1}{\dfrac{1}{2}}\)

|7 - \(\dfrac{3}{4}x\)|  - \(\dfrac{3}{2}\) = 2

|7 - \(\dfrac{3}{4}\)\(x\)| = 2 + \(\dfrac{3}{2}\)

|7 - \(\dfrac{3}{4}x\)| = \(\dfrac{7}{2}\)

\(\left[{}\begin{matrix}7-\dfrac{3}{4}x=\dfrac{7}{2}\\7-\dfrac{3}{4}x=-\dfrac{7}{2}\end{matrix}\right.\) 

\(\left[{}\begin{matrix}\dfrac{3}{4}x=7-\dfrac{7}{2}\\\dfrac{3}{4}=7+\dfrac{7}{2}\end{matrix}\right.\)

\(\left[{}\begin{matrix}\dfrac{3}{4}x=\dfrac{7}{2}\\\dfrac{3}{4}x=\dfrac{21}{2}\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=\dfrac{14}{3}\\x=14\end{matrix}\right.\)

 5  - |\(x-3\)| = 5

       |\(x-3\)| = 5 - 5

      |\(x-3\)| = 0

      \(x-3\) = 0 

      \(x\) = 3

|\(\dfrac{7}{2}\) - 42| + 14 = 14 ( vô lý xem lại đề bài nhé em)

\(\dfrac{2}{3}\) - |\(x+2\)| = 2

     |\(x+2\)| = \(\dfrac{2}{3}\) - 2

    |\(x+2\)| = - \(\dfrac{4}{3}\)  

   |\(x+2\)| ≥ 0 ∀ \(x\)

Vậy \(x\in\) \(\varnothing\)

a: \(\dfrac{x}{0.9}=\dfrac{5}{6}\)

\(\Leftrightarrow x=\dfrac{3}{4}\)

b: \(\dfrac{-6}{x}=\dfrac{9}{-15}\)

\(\Leftrightarrow x=10\)

c: \(\dfrac{\dfrac{14}{15}}{\dfrac{9}{10}}=\dfrac{x}{\dfrac{3}{7}}\)

\(\Leftrightarrow x=\dfrac{3}{7}\cdot\dfrac{14}{15}:\dfrac{9}{10}=\dfrac{2}{5}\cdot\dfrac{10}{9}=\dfrac{20}{45}=\dfrac{4}{9}\)

4/5 x 15/11 x 2/9 = 8/33

4/7 x 2/5 + 4/7 x 3/5 = 4/7

( 5/7 + 7/8 ) x 2 =  89/28

2/14 + 3/7 - 3/14 x 2 = 1/7 

tk mình nhé, mk nhanh nhất

4/5 x 15/11 x2/9

= 4x15x2/5x11x9

= 4x5x3x2/5x11x3x3

= 8/33

4/7x2/6+4/7x3/5

=4/7x(2/6+3/5)

=4/7x 14/15

=8/15

\(\frac{9}{14}-\frac{x}{7}:\frac{5}{3}=\frac{3}{14}\Leftrightarrow\frac{9}{14}-\frac{3x}{35}=\frac{3}{14}\Leftrightarrow\frac{3x}{35}=\frac{3}{7}\Leftrightarrow3x=15\Leftrightarrow x=5\)

9/14-x/7:5/3=6/14

x/7:5/3=3/14

x/7=5/14

x=35/7

X = 35 thôi

Ghi thiếu dấu "\(" 

`\sqrt{(x-5)-(x-14)}/(3+sqrt{x-5})=3`

Điều kiện:`x>=5`

`pt<=>\sqrt{x-5-x+14}/(3+sqrt{x-5})=3`

`<=>sqrt9/(3+sqrt{x-5})=3`

`<=>3/(3+sqrt{x-5})=3`

`<=>1//(3+sqrt{x-5})=1`

`<=>3+sqrt{x-5}=1`

`<=>sqrt{x-5}=-2`(vô lý)

Vậy pt vô nghiệm 

\sqrt{(x-5)-(x-14)}/(3+sqrt{x-5})=3`

Điều kiện:`x>=5`

`pt<=>\sqrt{x-5-x+14}/(3+sqrt{x-5})=3`

`<=>sqrt9/(3+sqrt{x-5})=3`

`<=>3/(3+sqrt{x-5})=3`

`<=>1//(3+sqrt{x-5})=1`

`<=>3+sqrt{x-5}=1`

`<=>sqrt{x-5}=-2`(vô lý)

Vậy pt vô nghiệm 

x/7=2/7

x=2

x/7 * 3/5 =3/7

x/7         =3/7:3/5

x/7          =5/7

x=5

x/7=5/7

x=5

sorry minh nham