b) -26 - ( x - 7 ) = 0

               x - 7   = -26 - 0

                x - 7  = -26

                x        = -26 + 7

                 x       = -19

Bài 2 :

a) 3 - ( 17 - x ) = -12

          ( 17 - x ) = 3 - ( -12 )

          ( 17 - x ) = 15

                    x  = 17 - 15

                    x  = 2

b) -26 - ( x - 7)=0

             x - 7 = -26 -0

            x - 7 = -26

              x = -26 + 7

             x = -19

\(a,\left(x-7\right):5=0\)

\(\Rightarrow x-7=0\)

\(\Rightarrow x=7\)

\(b,\left(x:7-7\right)\left(x:12-12\right)=0\)

\(\Rightarrow\hept{\begin{cases}x:7=7\\x:12=12\end{cases}}\)

\(\Rightarrow x=1\)

\(c,300-x:5=273\)

\(\Rightarrow x:5=27\)

\(\Rightarrow x=27.5=135\)

\(d,135+x:2=150\)

\(\Rightarrow x:2=15\)

\(\Rightarrow x=30\)

a) \(\left(x-7\right):5=0\)

\(\Rightarrow x-7=0\times5\)

\(\Rightarrow x-7=0\)

\(\Rightarrow x=0+7\)

\(\Rightarrow x=7\)

Vậy x = 7

b) \(\left(x:7-7\right)\left(x:12-12\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x:7-7=0\\x:12-12=0\end{cases}}\Rightarrow\orbr{\begin{cases}x:7=7\\x:12=12\end{cases}}\Rightarrow\orbr{\begin{cases}x=49\\x=144\end{cases}}\)

Vậy x = 49 hoặc x = 144

c) \(300-x:5=273\)

\(\Rightarrow x:5=300-273\)

\(\Rightarrow x:5=27\)

\(\Rightarrow x=27\times5\)

\(\Rightarrow x=135\)

Vậy x = 135

d) \(135+x:2=150\)

\(\Rightarrow x:2=150-135\)

\(\Rightarrow x:2=15\)

\(\Rightarrow x=15\times2\)

\(\Rightarrow x=30\)

Vậy x = 30

_Chúc bạn học tốt_

a) x - 7 = 5. 0 => x - 7 = 0 =>x = 7.

b) x: 3 = 47 +13 => x: 3 = 60 => x = 60.3 => x = 180.

c) x :  7 - 7 = 0 hoặc x : 12 - 12 = 0. Do đó x = 49 hoặc x = 144.

d) x : 2 = 150 - 135 => x: 2 = 15 => x = 15.2 => x = 30.

e) 100: x = 140 -120 => 100: x = 20 => x = 100:20 => x = 5.

g) x : 5 = 300 - 273 => x : 5 = 27 =>x = 27.5 => x = 135

a) x - 7 = 5. 0 => x - 7 = 0 =>x = 7.

b) x: 3 = 47 +13 => x: 3 = 60 => x = 60.3 => x = 180.

c) x :  7 - 7 = 0 hoặc x : 12 - 12 = 0. Do đó x = 49 hoặc x = 144.

d) x : 2 = 150 - 135 => x: 2 = 15 => x = 15.2 => x = 30.

e) 100: x = 140 -120 => 100: x = 20 => x = 100:20 => x = 5.

g) x : 5 = 300 - 273 => x : 5 = 27 =>x = 27.5 => x = 135

a, x=5

b,x=20

c,x=1 hoặc x=-2

d, ko hiểu đề bài

e,x=2

f,x=80

\(a)\left(x-5\right).2=0\)

\(\Rightarrow x-5=0\)

\(\Rightarrow x=5\)

Vậy \(x=5\)

\(b)x.3-13=47\)

\(\Rightarrow x.3=47+13\)

\(\Rightarrow x.3=60\)

\(\Rightarrow x=60:3\)

\(\Rightarrow x=20\)

Vậy \(x=20\)

\(c)\left(x.7-7\right)\left(x.12+24\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x.7-7=0\Rightarrow x.7=7\Rightarrow x=1\\x.12+24=0\Rightarrow x.12=-24\Rightarrow x=-2\end{cases}}\)

Vậy\(x\in\left\{1;-2\right\}\)

\(e)140-10.x=120\)

\(\Rightarrow10.x=140-120\)

\(\Rightarrow10.x=20\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

\(g)x.5-127=273\)

\(\Rightarrow x.5=273+127\)
\(\Rightarrow x.5=400\)

\(\Rightarrow x=400:5\)

\(\Rightarrow x=80\)

Vậy \(x=80\)

a) \(\left(2x+7\right)+135=0\)

\(2x+7=0-135\)

\(2x+7=-135\)

\(2x=-135-7\)

\(2x=-142\)

\(x=-142:2\)

\(x=-71\left(tm\right)\)

Vậy \(x=-71\)

a) (2x+7) + 135 = 0

2x+7= -135

2x= -135-7

2x=-142

x= -142 : 2=-71

b) (162 +3x) +(x-2)=0

162+ 3x + x-2=0

162+ x(3+1)-2=0

x.4= 0-162 +2

x.4= -160

x= -160: 4= -40

Chúc bạn học tốt

           Bài làm :

\(a\text{)}...\Leftrightarrow\orbr{\begin{cases}x\div7-7=0\\x.3-12=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x\div7=7\\x.3=12\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=49\\x=4\end{cases}}\)

\(b\text{)}\Leftrightarrow...\Leftrightarrow x\div2=15\Leftrightarrow x=15.2=30\)

\(c\text{)}...\Leftrightarrow100\div x=20\Leftrightarrow x=100\div20=5\)

\(d\text{)}...\Leftrightarrow x\div5=27\Leftrightarrow x=27.5=135\)

e: =>x=0 hoặc x=1

a:565-13.x=30

13.x=565-370

13.x=195

x=195:13

x=15

Nếu sai sót gì thì e xin lỗi ạ ^^

1/ Tính hợp lí:

\(\text{a/ ( - 16 ). ( - 25 ). ( - 12)}\)

\(=400.\left(-12\right)\)

\(=-4800\)