Решите уравнения:

(x^2-4x) ^2+9 (x^2-4x) + 20=0;

(x^2+x) (x^2-x-5) = 84

1) (x^2 - 4x) ^2 + 9 (x^2 - 4x) + 20 = 0

x^4 - 8x^3 + 16x^2 + 9x^2 - 36x + 20 = 0

x^4 - 2x^3 - 6x^3 + 25x^2 - 26x - 10x + 20 = 0

x^4 - 2x^3 - 6x^3 + 12x^2 + 13x^2 - 26x - 10x + 20 = 0

x^3 * (x - 2) - 6x^2 * (x - 2) + 13x (x - 2) - 10 (x - 2) = 0

(x - 2) (x^3 - 6x^2 + 13x - 10) = 0

(x - 2) (x^3 - 2x^2 - 4x^2 + 8x + 5x - 10) = 0

(x - 2) (x^2 * (x - 2) - 4x (x - 2) + 5 (x - 2)) = 0

(x - 2) (x - 2) (x^2 - 4x + 5) = 0

(x - 2) ^2 * (x^2 - 4x + 5) = 0

(x - 2) ^2 = 0

x^2 - 4x + 5 = 0

x = 2

x ∉ R

Ответ: x = 2

2) Второе не решается. Только графиком ...