Ответ:

1) 12 - (х-2) = 3

12-х +2 =3

14-3=х

х=11

2) 7(2х-3)-х= 3х-11

14х-21-х=3х-11

14х-х-3х = 21-11

10х=10

х=1

3) -4х+34=-2(х-5)

-4х+34=-2х+10

-4х+2х=10-34

-2х=-24

х = 12

4) -(х-3)+2(3-х)=12

-х+3+6-2х=12

-3х=12-6-3

-3х=3

х = -1

5) 23х-2(3х-4)=12

23х-6х+8=12

17х=4

х = 4/17

6) 23(х+2)-(2х-1)=1

23х+46-2х+1=1

21х=1-1-46

21х=-46

×= -46/21 = -2 4/21

7) 2(3-х)-21(х-1)=0

6-2х-21х+21=0

-23х=-21-6

-23х=-27

х = 27/23 = 1 4/23

8) -2(х-2)+3(2х-1) =0

-2х+4+6х-3=0

4х=3-4

4х=-1

х = - 0,25

9) -12(2х-1)-(х-1)=х

-24х+12-х+1=х

-24х-х-х=-1-12

-26х = - 13

х= 13/26 = 0,5