=>71-24+3x=23

=>3x=-24

hay x=-8

câu hỏi này e đã đăng r mà

x = -8 

-27 + 5( x-7 ) = 23 - (71-3x)

-27 + 5( x-7 ) = 23 - 71 + 3x

5(x-7) - 3x = 23 - 71 + 27

5x - 35 - 3x = -21

x( 5-3 ) - 35 = -21

x.2 - 35 = -21

x.2 = -21 + 35

x.2 = 14

x = 7

Vậy x = 7

-27+5(x-7)=23-(71-3x)
=>-27+5x-35=23-71+3x
=>-27-35-23+71=3x-5x
=>-14=-2x
=>-2x=-14
=>x=-14:(-2)
=>x=7
Vậy x=7

Dễ vậy ,tự làm đi bn

\(a,30\cdot6+30\cdot71+20\cdot30\)

=\(30\cdot\left(6+71+20\right)\)

=\(30\cdot97=2910\)

\(b,24\cdot\left(31+119\right)+76\cdot\left(29+121\right)\)

=\(24\cdot150+76\cdot150\)

=\(150\cdot\left(24+76\right)\)

=\(150\cdot100\)

=\(15000\)

\(c,87\cdot23+70\cdot87+43\cdot93\)

=\(87\cdot\left(23+87\right)+43\cdot93\)

=\(87\cdot110+3999\)

=\(9570+3999\)

=13569

a) 15 . 6 . 2 + 3 . 71 . 10 + 20 . 30 

= ( 15 . 2 ) . 6 + ( 3 . 10 ) . 71 + 20 . 30

= 30 . 6 + 30 . 71 + 20 . 30 

= 30 . ( 6 + 71 + 30 ) 

= 30 . 107

= 3210

b) 24 . 31 + 24 . 119 + 76 . 29 + 76 . 121 

= 24 . ( 31 + 119 ) + 76 . ( 29 + 121 )

= 24 . 150 + 76 . 150 

= 150 . ( 24 + 76 ) 

= 150 . 100 

= 15 000

c) 87 . 23 + 43 . 93 + 70 . 87 

= 87 . 23 + 70 . 87 + 43 . 93 

= 87 . ( 23 + 70 ) + 43 . 93 

= 87 . 93 + 43 . 93 

= 93 . ( 87 + 43 ) 

= 93 . 130 

= 12 090

a) 15 . 6 . 2 + 3 . 71 . 10 + 20 . 30

= 30 . 6 + 30 . 71 + 30 . 20

= 30 . (6 + 71 + 20) = 30 . 97 = 2910

b) 24 . 31 + 24 . 119 + 76 . 29 + 76 . 121

= 24 . (31 + 119) + 76 . (29 + 121)

= 24 . 150 + 76 . 150 = 150 . (24 + 76)

= 150 . 100

= 15000

c) 87 . 23 + 43 . 93 + 70 . 87

= 43 . 93 + 87 . (23 + 70)

= 43 . 93 + 87 . 93

= 93 . (43 + 87)

= 93 . 130

= 12090

Lời giải:
a.

$(x-15).27=0$

$x-15=0:27=0$

$x=15+0=15$

b.

$23(42-x)=0$

$42-x=0$

$x=42$

c.

$(9x+2).3=60$

$9x+2=60:3=20$

$9x=18$

$x=2$
d.

$71+(26-3x):5=75$

$(26-3x):5=75-71=4$

$26-3x=4.5=20$

$3x=26-20=6$

$x=6:2=3$

a) (71+x)-(-24-x)+(-35-x)=0                                    b)x-34-[(15+x)-(23-x)]=0

     71+x+24+x+-35-x    =0                                      x-34-15-x-23+x       =0

      (x+x-x)+(71+24-35) =0                                     (x-x+x)+(-34-15-23)  =0

              x+60             =0                                              x+-72             =0

              x                   =0-60                                         x                    =0-(-72)

              x                  = -60                                           x                    = 72

a/ M = (71+x)-(-24+x)+(-35-x) = 71 + x + 24 - x - 35 - x = (71 + 24 - 35) - x = 95 - 35 - x = 60 - x

b/ N=x-34-[(15+x)-(23-x)] = x - 34 - (15 + x - 23 + x) = x - 34 - (-8 + 2x) = x - 34 + 8 - 2x = -26 - x

\(a,M=\left(71+x\right)-\left(-24+x\right)+\left(-35-x\right)\)

        \(=71+x+24-x-35-x\)

        \(=60-x\)

\(b,N=x-34-\left[\left(15+x\right)-\left(23-x\right)\right]\)

       \(=x-34-\left(15+x-23+x\right)\)

       \(=x-34-15-x+23-x\)

       \(=-26-x\)

a) M=(71+x)-(-24+x)+(-35-x)

      = 71+x-(-24)-x+(-35)-x

      = (-24+71)+(-35)+(x-x-x)

      = 47+(-35)+(-x)

      = 12+(-x)

      = 12-x

 Vậy M=12-x

mk chỉ làm ý A thui nha

\(A=\left(71+x\right)-\left(-24-x\right)+\left(-35-x\right)\)

\(A=71+x+24+x+\left(-35\right)-x\)

\(A=\left[71+24+\left(-35\right)\right]+\left(x+x-x\right)\)

\(A=60+x\)

Vậy \(A=60+x\)

\(a,A=\left(71+x\right)-\left(-24-x\right)+\left(-35-x\right)\)

       \(=71+x+24+x-35-x\)

       \(=60+x\)

\(b,B=x-34-\left[\left(15+x\right)-\left(23-x\right)\right]\)

       \(=x-34-\left(15+x-23+x\right)\)

       \(=x-34-15-x+23-x\)

       \(=-x-26\)

a) A = (71 + x) - (-24 - x) + (-35 - x)

A = 71 + x + 24 + x + (-35) - x

A = (x + x - x) + (71 + 24 + (-35)
A = x + 60

b) B = x - 34 - [(15 + x) - (23 - x)]

B = x - 34 - [15 + x - 23 + x]

B = x - 34 - 15 - x + 23 - x

B = (x - x - x) + (-34 - 15 + 23)

B = -x + (-26)

c) C = (-15 + |x|) + (25 - |-x|)

C = (-15) + x + 25 - (-x)

C = (-15) + x + 25 + x

C = (x + x) + [(-15) + 25]

C = 2x + 10

a) ( 71 + x ) - ( -24 - x ) + ( -35 - x )

= 71 + x + 24 + x - 35 - x

= ( 71 + 24 - 35 ) + ( x + x - x )

= 60 + x

b) x - 34 - [( 15 + x ) - ( 23 - x )]

= x - 34 - ( 15 + x - 23 + x )

= x - 34 - ( 15 - 23 + x2 )

= x - 34 - ( - 8 + 2x )

= x - 34 + 8 - 2x

= x - 2x + 8 - 34

= -x - 26

c) ( -15 + |x| ) + ( -25 - |x| )

= -15 + |x| - 25 + |x|

= -15 - 25 + x + x

= -40 + x2

a)(71+x)-(-24-x)+(-35-x)

=>71+x+24+x-35-x

=>60+x

b)x-34-[(15+x)-(23-x)]

=>x-34-(15+x-23+x)

=>x-34-15-x+23-x

=-x-26

71 + ( 26 - 3 . x ) ; 5 = 75 

        ( 26 - 3x ) : 5 = 75 - 71 

         ( 26 - 3x ) : 5 = 4 

          26 - 3x = 4.5 

          26 - 3x = 20

               3x = 26 - 20

               3x = 6

                x = 6 : 3 

                x = 2

a/ (71+x) - [(-24) - x] + [(-35) - x ]=71+x+24+x-35-x=x+60

b/ x - 34 - [(15 + x) - (23 - x)]=x-34-15-x-23+x=x-72

c/ 26 - [(-x) + 126 - 13) + [(-113) + x]=26+x-126+13-113+x=2x-200=2(x-100)