Решите уравнения: 5y+(8y+9)=100 x-(50-x)=12 4(x-7)=3x+5 -5x+3(3+2x)=7

Найдем корни:

1) 5 * y + (8 * y + 9) = 100; 

Скобки раскроем.

5 * y + 8 * y + 9 = 100;

y * (5 + 8) + 9 = 100;

y * 13 + 9 = 100;

13 * y + 9 = 100;

13 * y = 100 - 9;

13 * y = 81;

y = 81/13. 

2) x - (50 - x) = 12; 

x - 50 + x = 12;

2 * x - 50 = 12;

x - 25 = 6;

x = 6 + 25;

x = 31.

3) 4 * (x - 7) = 3 * x + 5; 

4 * x - 4 * 7 = 3 * x + 5;

4 * x - 28 = 3 * x + 5;

4 * x - 3 * x = 5 + 28;

x = 33.

4) -5 * x + 3 * (3 + 2 * x) = 7;  

-5 * x + 3 * 3 + 3 * 2 * x = 7; 

-5 * x + 9 + 6 * x = 7; 

x + 9 = 7; 

x = 7 - 9; 

x = -2.