Первый способ
x^2 (x - 4) - (x - 4) = 0
(x - 4)(x^2 - 1) = 0
(x - 4)(x - 1)(x + 1) = 0
x1 = 4
x2 = 1
x3 = - 1
x1^2 + x2^2 + x3^2 = 16 + 1 + 1 = 18
Второй способ
x1 + x2 + x3 = 4
x1*x2 + x1*x3 + x2*x3 = - 1
x1*x2*x3 = - 4
p2 = e1^2 - 2e2 = 4^2 - 2*(-1) = 16 + 2 = 18