Х^4-11 х^2+30=0 Х * (х+1) - (х+2) (х+3) + 8=х * (х+4) - (х+5) (х+2)

1). x^4 - 11 х² + 30 = 0;

Заменим x² = y;

y² - 11 y + 30 = 0;

D = 121 - 120 = 1;

y = (11 ± √1) : 2;

y = (11 + 1) : 2; y = 6;

y' = (11 - 1) : 2; y' = 5;

x = √y;

x = √6; x' = - √6; x'' = √5; x''' = - √5;

2). x * (х + 1) - (х + 2) (х + 3) + 8 = х * (х + 4) - (х + 5) (х + 2);

x² + x - x² - 2 x - 3 x - 6 + 8 = x² + 4 x - x² - 5 x - 2 x - 10;

- 4 x + 2 = - 3 x - 10;

x = 12.