( 2600 + 6400 ) - 3 . x = 1200

9000 -3x =1200

3x = 9000-1200= 7800

x = 7800 : 3

x =2600

( 2600 + 6400 ) - 3 . x = 1200

=> 9000 -3x =1200

=> 3x = 9000-1200= 7800

=> x = 7800 : 3

=> x = 2600

9000-3.x=1200

=> 3x= 9000-1200

=>3x=7800

=>x=7800:3=2600

t i c k cho mình nha

(2600 + 6400) - 3.x = 1200

             9000 - 3.x = 1200

                        3.x = 9000 - 1200

                         3.x = 7800

                            x = 7800 : 3

                            x = 2600

<=>9000-3x=1200

<=> 9000-1200=3x

<=>7800=3x

<=>x=260

(2600+6400)-3.x=1200

          9000-3.x =1200

                  3.x =9000 -1200

                 3.x  =7800

                   x   = 7800 :3 

                   x   = 2600

(2600+6400)-3x=1200

10 000-3x=1200

3x=9000-1200

3x=7 800

x=7800/3

x=2600

(2600+6400)-3x=1200

<=>9000-3x=1200

<=>3x=9000-1200

<=>3x=7800

<=>x=2600

[(6.x-72):2-84].28=5628

=>9000-3x=1200

=>3x=9000-1200

=>3x=7800

=>x=7800:3

=>x=2600

(2600+6400)-3.x=1200

=>9000-3.x=1200

=>3.x=9000-1200

=>3.x=7800

=>x=7800:3

=>x=2600

\(\left(2600+6400\right)-3.X=1200\)

\(9000-3.X=1200\)

\(3.X=9000-1200\)

\(3.X=7800\)

\(X=7800:3\)

\(X=2600\)

(2600+6400)-3xX=1200

⇒ 9000-3xX=1200

⇒ 3xX=9000-1200=7800

⇒ X=7800:3=2600

⇒ X=2600

\(\left(2600+6400\right)-3\times x=1200\)

\(9000-3.x=1200\)

\(3.x=9000-1200\)

\(3.x=7800\)

\(x=7800:3\)

\(x=2600\)

\(\left(2600-6400\right)-3x=1200\\ -3800-3x=1200\\ 3x=-3800-1200\\ 3x=-5000\\ x=-5000:3\\ x=\dfrac{-5000}{3}\)

\(\left(3x-1\right)^3=125\\ \left(3x-1\right)^3=5^3\\ 3x-1=5\\ 3x=6\\ x=6:3\\ x=2\)

(2600 + 6400) – 3x = 1200

9000 – 3x = 1200

3x = 9000 - 1200

3x = 7800

x = 7800 : 3

x = 2600

Vậy x = 2600

a,(2600+6400)-3 .x = 1200

=> 9000-3 .x= 1200

=> 3.x= 7800

=. x=2600

b, (6.x-72):2-84= 201

(6x-72):2=285

6x-72=570

6x=642

x=107

a) ( 2600 + 6400 ) - 3 . x = 1200

             9000       - 3 . x = 1200

                             3 . x = 9000 - 1200

                             3 . x =        7800

                                  x = 7800 : 3

                                  x =        2600

Ban kia lam dung roi do 

k tui nha

thanks

a) x = 7797

a) \(\left(2600+6400\right)-3-x=1200\)

\(\Rightarrow9000-3-x=1200\)

\(\Rightarrow3-x=9000-1200\)

\(\Rightarrow3-x=7800\)

\(\Rightarrow x=7797\)

b) \(\left[\left(6\cdot x-72\right):2-84\right]\cdot28=5628\)

\(\Rightarrow\left[\left(6\cdot x-72\right):2-84\right]=5628:28\)

\(\Rightarrow\left[\left(6\cdot x-72\right):2-84\right]=201\)

\(\Rightarrow\left(6\cdot x-72\right):2=201+84\)

\(\Rightarrow\left(6\cdot x-72\right):2=285\)

Đến dei bạn tự làm, ý b mình không chắc chắn lắm

x=107