Решите уравнения

1) x^2-5 = (x+5) (2x-1)

2) (2x+3) (3x+1) = 11x+30

3) 2x - (x+1) ^2=3x^2-6

4) 6a^2 - (a+2) ^2 = - 4 (a-4)

5) x (7-6x) = (1-3x) (1+2x)

6) (5y+2) (y-3) = - 13 (2+y)

x^2-5 = (x+5) (2x-1)

x^2 - 5 = 2x^2 - x + 10x - 5

2x^2 - x^2 - x - 10x - 5 + 5 = 0

x^2 - 9x = 0

x * (x - 9) = 0

x = 0 или x = 9

(2x+3) (3x+1) = 11x+30

6x^2 + 2x + 9x + 3 = 11x + 30

6x^2 + 11x - 11x = 30 - 3

6x^2 = 27

2x^2 = 9

x^2 = 9/2

x = 3 / √ 2

2x - (x+1) ^2=3x^2-6

2x - x^2 - 1 - 2x = 3x^2 - 6

3x^2 + x^2 = 5

4x^2 = 5

x^2 = 5/4

x = √5/2

6a^2 - (a+2) ^2 = - 4 (a-4)

6a^2 - a^2 - 4 - 4a = - 4a + 16

5a^2 = 20

a^2 = 4

a = 2

x (7-6x) = (1-3x) (1+2x)

7x - 6x^2 = 1 + 2x - 3x - 6x^2

7x - 2x + 3x = 1

8x = 1

x = 1/8

(5y+2) (y-3) = - 13 (2+y)

5y^2 - 15y + 2y - 6 = - 26 - 13y

5y^2 - 13y + 13y = - 26 + 6

5y^2 = - 20

y^2 = - 4

y = решений нет, поскольку из отрицательного числа квадратный корень извлечь невозможно.