X^2 + 64 = 0
x^2 = - 64 - корней нет
x^2 - 144 = 0
x^2 = 144
x1 = 12
x2 = - 12
x^2 + 25 = 0
x^2 = - 25 - корней нет
x^2 - 5 = 0
x^2 = 5
x1 = √5
x2 = - √5
(x - 1)^2 = 9
x^2 - 2x + 1 - 9 = 0
x^2 - 2x - 8 = 0
D = 4 + 32 = 36 = 6^2
x1 = ( 2 + 6) / 2 = 4
x2 = ( 2 - 6) / 2 = - 2
(x+ 5)(x+ 5) = 0
x + 5 = 0
x = - 5