Question

ПОМОГИТЕ ПОЖАЛУЙСТА!!! ДАЮ 20 БАЛЛОВ!! НАДО С ПРОВЕРКОЙ!!​

Answer 1

21) 3x-1 = 2·(x-2)

3x-1 = 2x-4

3x-2x = -4+1

x = -3

Проверка (подставляем x поочереди в обе части уравнения):

3x-1 = 3·(-3)-1 = -9-1 = -10

2·(x-2) = 2·(-3-2) = 2·(-5) = -10

-10 = -10

22) 3·(x+5) = 7-5x

3x+15 = 7-5x

3x+5x = 7-15

8x = -8

x = -1

Проверка:

3·(x+5) = 3·(-1+5) = 3·4 = 12

7-5x = 7-5·(-1) = 7+5 = 12

12 = 12

23) 19·(y-9) = 3·(y-8)

19y-171 = 3y-24

19y-3y = 171-24

16y = 147

y = 147/16 = 9 3/16

Проверка:

19·(y-9) = 19·(9 3/16-9) = 19·3/16 = 57/16

3·(y-8) = 3·(9 3/16-8) = 3·1 3/16 = 3·19/16 = 57/16

57/16 = 57/16

24) 4·(x-9) = 3·(x-8)

4x-36 = 3x-24

4x-3x = 36-24

x = 12

Проверка:

4·(x-9) = 4·(12-9) = 4·3 = 12

3·(x-8) = 3·(12-8) = 3·4 = 12

12 = 12

25) 3·(2x-9) = 5·(x-4)

6x-27 = 5x-20

6x-5x = 27-20

x = 7

Проверка:

3·(2x-9) = 3·(2·7-9) = 3·(14-9) = 3·5 = 15

5·(x-4) = 5·(7-4) = 5·3 = 15

15 = 15