-х^4-4х^2+5=0 !!!!!!!!
- x^4 - 4x^2 + 5 = 0 x^4 + 4x^2 - 5 = 0 (x^2 + 5)(x^2 - 1) = 0 x^2 = - 5 нет решений x^2 = 1 x1 = - 1 x2 = 1