( х^2 + 8х )( х^2 + 8х - 6 ) = 280
Х^2 + 8х = а
а( а - 6 ) = 280
а^2 - 6а - 280 = 0
D = 36 + 1120 = 1156 = 34^2
a1 = ( 6 + 34 ) : 2 = 20
a2 = ( 6 - 34 ) : 2 = - 14
1) x^2 + 8x = 20
X^2 + 8x - 20 = 0
D = 64 + 80 = 144 = 12^2
X1 = ( - 8 + 12 ) : 2 = 2
X2 = ( - 8 - 12 ) : 2 = - 10
2) x^2 + 8x = - 14
X^2 + 8x + 14 = 0
D = 64 - 56 = 8 ; кв корень ( V8 ) = 2V2
X1 = ( - 8 + 2V2 ) : 2 = - 4 + V 2 ;
X2 = - 4 - 2V2
Ответ 2 ; - 10 ; - 4 + V 2 ; - 4 - V 2