-12(x-5)+7(3-x)=5

-12.x+60+21-7.x=5

-19.x=76

=> không có x

Minh cung giai giong nhu vay nhung khuc cuoi

-19.x=76

suy ra x=-4

=> -12x+60+21x=5
=>9x -55=0
=>x=\(\frac{55}{9}\)

\(-12\left(x-5\right)+7\left(3x\right)=5\)

\(\Rightarrow-12x+60+21x=5\)

\(\Rightarrow-12x+21x+60=5\)

\(\Rightarrow9x+60=5\)

\(\Rightarrow9x=5-60\)

\(\Rightarrow9x=-55\)

\(\Rightarrow x=\frac{-55}{9}\)

\(43+\left(9-21\right)=317\left(x+317\right)\)

\(\Rightarrow317-\left(x+317\right)=43+\left(9-21\right)\)

\(\Rightarrow317-\left(x+317\right)=43+\left(-12\right)\)

\(\Rightarrow317-\left(x+317\right)=31\)

\(\Rightarrow x+317=317-31\)

\(\Rightarrow x+317=286\)

\(\Rightarrow x=286-317\)

\(\Rightarrow x=-31\)

Vay x = -31

\(b.\left(15-x\right)+\left(x-12\right)=7-\left(-5+x\right)\)

\(\Rightarrow15-x+x-12=7+5+x\)

\(\Rightarrow15-12=12-x\)

\(\Rightarrow3=12-x\)

\(\Rightarrow12-x=3\)

\(\Rightarrow x=12-3\)

\(\Rightarrow x=9\)

Vay x = 9 

....

a) 43+(9-21) = 317-(x+317)

43+(-12) = 317-(x+317)

317-(x+317) = 31

x+317 = 317-31=286

x = 286-317=(-31)

Tạm thời câu b mình chưa nghĩ ra nha.

a) \(43+\left(9-21\right)=317-\left(x+317\right)\)

\(43+\left(-12\right)=317-\left(x+317\right)\)

   \(317-\left(x+317\right)=31\)

\(x+317=317-31=286\)

\(x=286-317=-31\)

b) \(\left(15-x\right)+\left(x-12\right)=7-\left(-5+x\right)\)

\(15-x+x-12=7+5-x\)

\(7+5-x=\left(15-12\right)+\left(-x+x\right)\)

\(7+5-x=3+0=3\)

\(5-x=3-7=-4\)

\(x=5-\left(-4\right)=5+4=9\)

a)-12(x-5)+7(3-x)=5

-12x-(-60)+21-7x=5

-12x+60+21-7x=5

-12x-7x=5-60-21

-19x=-76

x=-76/-19

x=4. Vậy x=4

ặc, bạn ghi ít ít thôi, ghi thế này nhiều quá

1 )

-12( x - 5 ) + 7( 3 - x ) = 5

<=> -12x + 60 + 21 -7x = 5 

<=> -12x -7x                 = 5 - 21 - 60

<=>    -19x                     =  -76

<=>          x                    = \(\frac{-76}{-19}\)

<=>         x                     =  4 

giúp mình câu 2 đi

\(1)\)

\(-12\left(x-5\right)+7\left(3-x\right)=5\)

\(\Rightarrow-12x--12.5+7.3-7x=5\)

\(\Rightarrow-12x-\left(-60\right)+21-7x=5\)

\(\Rightarrow-12x+60+21-7x=5\)

\(\Rightarrow-19x+81=5\)

\(\Rightarrow-19x=5-81\)

\(\Rightarrow-19x=-76\)

\(\Rightarrow x=-76:-19\)

\(\Rightarrow x=4\)

Vậy \(x=4\)

\(2)\)

Ta có : 

\(\left|x\right|< 3\Rightarrow\left|x\right|\in\left\{0;1;2\right\}\)

Với \(\left|x\right|=0\Rightarrow x=0\)

Với  \(\left|x\right|=1\Rightarrow\orbr{\begin{cases}x=1\\x=-1\end{cases}}\)

Với \(\left|x\right|=2\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)

Vậy  \(x\in\left\{0;1;-1;2;-2\right\}\)

~ Ủng hộ nha