\(a,\frac{x+8}{3}+\frac{x+7}{2}=-\frac{x}{5}\)

\(\Leftrightarrow\frac{10\cdot\left(x+8\right)}{30}+\frac{15\left(x+7\right)}{30}=\frac{-6x}{30}\)

\(\rightarrow10x+80+15x+105=-6x\)

\(\Leftrightarrow31x+185=0\)

\(\Leftrightarrow x=-\frac{185}{31}\)

b,\(b,\frac{x-8}{3}+\frac{x-7}{4}=4+\frac{1-x}{5}\)

\(\Leftrightarrow\frac{20\left(x-8\right)}{60}+\frac{15\left(x-7\right)}{60}=\frac{240}{60}+\frac{12\left(1-x\right)}{60}\)

\(\rightarrow20x-160+15x-105=240+12-12x\)

\(\Leftrightarrow47x-517=0\)\(\Leftrightarrow x=11\)

`3/7xx14/5+32/5xx3/7+3/7xx9/5`

`=3/7xx(14/5+32/5+9/5)`

`=3/7xx55/5`

`=3/7xx5`

`=15/7`

\(=\frac{3}{7}\times[\frac{14}{5}+\frac{32}{5}+\frac{9}{5}]=\frac{3}{7}\times\frac{55}{5}=\frac{3}{7}\times11=\frac{33}{7}\)

a) \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)

⇔\(7\left(x-3\right)=5\left(x+5\right)\)

⇔\(7x-21=5x+25\)

⇔\(7x-21-5x-25=0\)

⇔\(2x-46=0\)

⇔\(2x=46\)

⇔\(x=23\)

b) \(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)

⇔\(\left(x+1\right)\left(x-1\right)=7.9\)

⇔\(x^2-1=63\)

⇔\(x^2=64=8^2\)

⇔\(\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)

\(a.\dfrac{x-3}{x+5}=\dfrac{5}{7}\)                          

    \(\left(x-3\right).7=\left(x+5\right).5\) 

    \(\left(x.7\right)+\left[\left(-3\right).7\right]=\left(x.5\right)+\left(5.5\right)\)

    \(7x-21=5x+25\)

    \(7x-5x=25+21\)

             \(2x=46\)

               \(x=46:2\)

               \(x=23\)

Câu b/ cứ làm theo câu a/ là được

AcCl₃ và NiCl₂

\(a,-\dfrac{12}{16}-\left(\dfrac{3}{4}-x\right)=-\dfrac{5}{3}\)

\(\dfrac{3}{4}-x=-\dfrac{12}{16}-\left(-\dfrac{5}{3}\right)\)

\(\dfrac{3}{4}-x=\dfrac{11}{12}\)

\(x=\dfrac{3}{4}-\dfrac{11}{12}\)

\(x=-\dfrac{1}{6}\)

\(b,x-\dfrac{3}{7}:\dfrac{9}{14}=-\dfrac{7}{3}\)

\(x-\dfrac{3}{7}=-\dfrac{7}{3}\times\dfrac{9}{14}\)

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

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

\(x=-\dfrac{15}{14}\)

\(c,-\dfrac{3}{4}x+\dfrac{5}{8}x=\dfrac{1}{3}\)

\(\left(-\dfrac{3}{4}+\dfrac{5}{8}\right)x=\dfrac{1}{3}\)

\(-\dfrac{1}{8}x=\dfrac{1}{3}\)

\(x=\dfrac{1}{3}:\left(-\dfrac{1}{8}\right)\)

\(x=-\dfrac{8}{3}\)

`-12/16 - ( 3/4 - x ) = -5/3`

`=> 3/4 - x=-12/16 -(-5/3)`

`=> 3/4 - x=-12/16 +5/3`

`=> 3/4 - x=11/12`

`=> x= 3/4-11/12`

`=> x=9/12 -11/12`

`=> x=-1/6`

__

`x - 3/7 : 9/14 = - 7/3`

`=>x - 3/7=-7/3 xx 9/14`

`=>x - 3/7=-3/2`

`=>x= -3/2 + 3/7`

`=>x=-15/14`

__

`-3/4 x + 5/8 x =1/3`

`=> (-3/4 + 5/8) x =1/3`

`=> ( -6/8+ 5/8) x =1/3`

`=> -1/8 x=1/3`

`=>x= 1/3 : (-1/8)`

`=> x= 1/3 xx (-8)`

`=>x= -8/3`

\(\left(x-\dfrac{4}{7}\right):-\dfrac{1}{3}=1\)
\(\Rightarrow x-\dfrac{4}{7}=1\cdot-\dfrac{1}{3}\)

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

\(\Rightarrow x=-\dfrac{1}{3}+\dfrac{4}{7}\)

\(\Rightarrow x=\dfrac{5}{12}\)

___________________

\(\dfrac{2}{3}-\dfrac{7}{4}:x=\dfrac{5}{6}\)

\(\Rightarrow\dfrac{7}{4}:x=\dfrac{2}{3}-\dfrac{5}{6}\)

\(\Rightarrow\dfrac{7}{4}:x=-\dfrac{1}{6}\)

\(\Rightarrow x=\dfrac{7}{4}:-\dfrac{1}{6}\)

\(\Rightarrow x=-\dfrac{21}{2}\)

(x - 4/7) : (-1/3) = 1

x - 4/7 = -1/3

x = -1/3 +4/7

x = 5/21

--------------------

2/3 + 7/4 : x = 5/6

7/4 : x = 5/6 - 2/3

7/4 : x = 1/6

x = 7/4 : 1/6

x = 21/2

a) ( x - 4/7) : (-1/3) = 1

      x- 4/7                = 1 . (-1/3)

         x                     =-1/3 + 4/7

         x                     =   5/12

b) 2/3 + 7/4 : x = 5/6

              7/4: x  = 2/3 -5/6

                     x   = 7/4  : (-1/6 )

                     x    =    -21/2

\(3\cdot\left(\dfrac{1}{2}-x\right)-5\left(x-\dfrac{1}{10}\right)=-\dfrac{7}{4}\\ \Leftrightarrow-8x=-\dfrac{15}{4}\\ \Leftrightarrow x=\dfrac{15}{32}\)

\(4\left(\dfrac{3}{4}+x\right)-\dfrac{1}{5}=7x-\dfrac{1}{7}\\ \Leftrightarrow3x=\dfrac{103}{35}\\ \Leftrightarrow x=\dfrac{103}{105}\)

\(3\left(\dfrac{1}{2}-x\right)-5\left(x-\dfrac{1}{10}\right)=-\dfrac{7}{4}\)

\(\Rightarrow\dfrac{3}{2}-3x-5x+\dfrac{1}{2}=-\dfrac{7}{4}\)

\(\Rightarrow2-8x=-\dfrac{7}{4}\)

\(\Rightarrow8x=2+\dfrac{7}{4}\)

\(\Rightarrow8x=\dfrac{15}{4}\)

\(\Rightarrow x=\dfrac{15}{32}\)

___________

\(4\left(\dfrac{3}{4}+x\right)-\dfrac{1}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow3+4x-\dfrac{1}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow4x+\dfrac{14}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow7x-4x=\dfrac{14}{5}+\dfrac{1}{7}\)

\(\Rightarrow3x=\dfrac{103}{35}\)

\(\Rightarrow x=\dfrac{103}{105}\)

`3(1/2 - x) - 5(x -1/10) = -7/4`

`=> 3/2 - 3x - 5x + 1/2 = -7/4`

`=> (-3x- 5x) + (3/2 + 1/2) = -7/4`

`=> -8x + 2 = -7/4`

`=>   -8x     = -15/4`

`=>      x     = 15/32`

`4(3/4 + x) - 1/5 = 7x - 1/7`

`=> 3 + 4x - 1/5 = 7x - 1/7`

`=> 4x + (3- 1/5) = 7x - 1/7`

`=> 4x + 14/5     = 7x - 1/7`

`=> 4x - 7x         = -14/5 - 1/7`

`=> -3x              = -103/35`

`=>    x              = 103/105`

a: \(-\dfrac{2}{5}+\dfrac{4}{5}x=\dfrac{3}{5}\)

=>\(\dfrac{4}{5}x=\dfrac{3}{5}+\dfrac{2}{5}=1\)

=>\(x=1:\dfrac{4}{5}=\dfrac{5}{4}\)

b; \(-\dfrac{3}{7}-\dfrac{4}{7}:x=-2\)

=>\(\dfrac{4}{7}:x+\dfrac{3}{7}=2\)

=>\(\dfrac{4}{7}:x=2-\dfrac{3}{7}=\dfrac{11}{7}\)

=>\(x=\dfrac{4}{7}:\dfrac{11}{7}=\dfrac{4}{11}\)

\(\text{4x+10=5(x-7) }\)

\(4x+10=5x+35\)

\(4x-5x=35-10\)

\(-x=25\)

\(x=-25\)

cảm ơn bạn nha

\(\left(\dfrac{5}{7}+x\right)\div\dfrac{4}{9}=\dfrac{2}{3}\)

\(\dfrac{5}{7}+x=\dfrac{2}{3}\times\dfrac{4}{9}\)

\(\dfrac{5}{7}+x=\dfrac{8}{27}\)

\(x=\dfrac{8}{27}-\dfrac{5}{7}\)

\(x=\dfrac{-79}{189}\)