(72 +X) : 9 = 9171:9

72 + X     =    9171

X  =   9171 - 72

 X     =   9099 

=> X x (12 - 9 - 2) = 72

=> X x 1 = 72 

=> X = 72

\(12\times x-9\times x-2\times x=72\\ =>x\times\left(12-9-2\right)=72\\ =>x\times1=72\\ =>x=72:1=72\)

72-3|x+1|=9

<=>3|x+1|=63

<=>|x+1|=21

Xét TH1: x+1>0

 <=>x+1=21

<=>x=20

Xét TH2: x+1<0

<=>x+1=-21

<=>x=-22

Vậy x=20 hoặc x=-22

( 12 - x ) x 9 = 72

( 12 - x )       = 72 : 9 

( 12 - x )       =  8

         x         = 12 - 8 

         x         = 4

( 12 - x ) x 9 = 72

      ( 12 - x ) = 72 : 9

      ( 12 - x ) = 8

               x = 12 - 8

               x = 4

Mik hứa sẽ tk lại ! Thanks !

(12-x)x9=72

12-x=72:9

12-x=8

    x=12-8

    x=4

72+40/9 = x+x*1/7

688/9 =x*(1+1/7)= x*8/7

x = 688/9 : 8/7 = 602/9

\(\dfrac{15}{8}\)

x : 5/9 = 3/72

      x : 5/9 = 1/24

      x = 1/24 x 5/9

      x = 5 / 216

\(x:\dfrac{5}{9}=\dfrac{3}{72}\)

\(x=\dfrac{3}{72}\cdot\dfrac{5}{9}\)

\(x=\dfrac{5}{216}\)

(-x). (+9)=72

=> -x.9=72

=> -x = 72 : 9

=> -x = 8

=> x = -8

vậy____

( - x ) . ( + 9 ) = 72

- x = 72 : 9

- x = 8

=> x = -8

Vậy x = -8

(2.x + 5)³ : 9 - 9 = 72

=> (2x + 5)³ : 9 = 91

=> (2x + 5)³ = 729

=> (2x + 5)³ = 9³

=> 2x + 5 = 9

=> 2x = 14

=> x = 7

vậy_