10) x^3 + 2x^2 - 9x - 18 = 0;
x^2(x + 2) - 9 ( x + 2) = 0;
(x+2)(x^2 - 9) = 0
1. x+2 =0 2. x^2 - 9 =0
x= -2; x^2 = 9;
x= + - 3;
6) x^2 + 8x +16 - x^2 = 2x + 1;
8x - 2x = 1 - 16;
6x = -15;
x = - 15 / 6;
x = - 2,5 ;
9) x^2( x - 3) + 2 (x -3) = 0;
(x - 3)(x^2 + 2) = 0
x - 3 = 0 x^2 + 2 =0
x = 3 x^2= -2 - нет решений
11) 7 - ( 8x^2 -6x - 2) = 10x - 8x^2;
7 - 8x^2 + 6x + 2 = 10x - 8x^2;
10x - 6x = 9 ;
4x = 9;
x = 9/4;
х = 2,25.
12) 25- 10x + x^2 - ( 6x^2 - x - 2) = 2x - 5x^2;
25 - 10x + x^2 - 6x^2 +x + 2 = 2x - 5x^2 ;
11x = 27;
x = 27/11;
x= 2 целых и 5/11;
Ответ: 6) - 2,5 ; 9) 3 ; 10) - 3 ; -2 ; 3 ; 11) 2,25; 12) 2 целых и 5/11.