1) - x( x -4) = 4
- x^2 + 4x - 4 =0
x^2 - 4x + 4 =0
D = 16 - 16 =0 - имеет одно решение
x = - b/2a
x= 4/2 = 2
x= 2
2) ( - x - 6)(x - 3) = 14
- x^2 + 3x - 6x + 18 - 14 = 0
x^2 + 3x - 4 = 0
D = 9 + 16 = 25 = 5^2
x1 = ( - 3 + 5) / 2 = 1
x2 =( - 3 - 5) / 2 = - 4
3) x - 1 = 8 - x^2 + x
x^2 = 9
x = 3
x = - 3
4) - x^2 - 3x = x + 4
- x^2 - 4x - 4 = 0
x^2 + 4x + 4 = 0
D = 16 - 16 = 0- имеет одно решение
x = - b/2a
x = - 4/2
x = - 2
5) x^2 - 4x = 2x - 8
x^2 - 6x + 8 = 0
D = 36 - 32 = 4 = 2^2
x1 = ( 6 + 2) / 2 = 4
x2 = ( 6 - 2)/ 2 = 2