1) 5x (3x-7) = 9 2) 3y - (5*y) = 11 3) 48=11 - (9a+2) 4) (7x+1) - (6x+3) = 5 5) (8x+11) - 13=9+-5

Решим уравнения:

1) 5 х * (3 х - 7) = 9;

15 х^2 - 35 х - 9 = 0.

D = b^2 - 4ac = 1225 + 4 * 15 * 9 = 1765.

x1 = (-b + √D) / 2a = (35 + √1765) / 30;

x2 = (-b - √D) / 2a = (35 - √1765) / 30.

2) 3y - (5 * y) = 11;

3y - 5y = 11;

-2y = 11;

y = 11 : (-2);

y = - 5,5.

3) 48 = 11 - (9a + 2);

48 = 11 - 9a - 2;

9a = 11 - 2 - 48;

9a = 9 - 48;

9a = - 39;

a = - 39/9;

a = - 4 1/3.

4) (7x + 1) - (6x + 3) = 5;

7x + 1 - 6x - 3 = 5;

7x - 6x = 5 - 1 + 3;

x = 4 + 3;

x = 7.

5) (8x + 11) - 13 = 9 + (-5);

8x = 9 - 5 - 11 + 13;

8x = 4 + 2;

8x = 6;

x = 6 : 8;

x = 3/4.