Решите уравнение: 1. 5 (3x + 1,2) + x = 6,8 2. - 3 (3y + 4) + 4 (2y - 1) = 0

1.

5 ⋅ (3 x + 1,2) + x = 6,8;

15 х + 6 + х = 6,8;

16 х + 6 = 6,8;

16 х = 6,8 - 6;

16 х = 0,8;

х = 0,8 : 16 = 0,05.

Проверим:

5 ⋅ (3 ⋅ 0,05 + 1,2) + 0,05 = 6,8;

5 ⋅ (0,15 + 1,2) + 0,05 = 6,8;

5 ⋅ 1,35 + 0,05 = 6,8;

6,75 + 0,05 = 6,8;

6,8 = 6,8.

2.

-3 ⋅ (3 y + 4) + 4 ⋅ (2 y - 1) = 0;

-3 ⋅ 3 y - 3 ⋅ 4 + 4 ⋅ 2 y - 4 = 0;

-9 y - 12 + 8 y - 4 = 0;

-y - 16 = 0;

-y = 16;

у = - 16.

Проверим:

-3 ⋅ (3 ⋅ (-16) + 4) + 4 ⋅ (2 ⋅ (-16) - 1) = 0;

-3 ⋅ (-48 + 4) + 4 ⋅ (-32 - 1) = 0;

144 - 12 - 128 - 4 = 0;

0 = 0.