Question

(x^2+3)^2-20(x^2+3)+19=0

Answer 1

x^2 + 3 = z
z^2 - 20z + 19 = 0
z1 = 1
z2 = 19
x^2 + 3 = 1
x^2 = - 2 нет решений
x^2 + 3 = 19
x^2 = 16
x1 = - 4
x2 = 4