Всем привет прошу кто чем может помогите с 35,36 и 43

35: 4x - 8x + c = 0;   x - x = 3,   x + x = 2,   2x = 5,  x = 2,5;  x = 2 - x = 2 - 2,5 = - 0,5;   c =4 0,5 2,5 = 5;   36: x + ax + 7 = 0;  x + x  = - a;   x  x = 7;   x + x = 8 x x  - 64 = 56 - 64= - 8 c = 8;    43:    x - 4x + 3 = 0;  x + x = 4,   x x = 31)  x x +  x x =  x x ( x  + x) = 3 4 = 12;  2) 1/x + 1/x = (  x + x) : (  x x ) = ( ( x + x) - 2x x) : ( x x) = (4 - 2 3) : 3 = 10/9

3) x/x + x/x + 2 = (x + 2xx + x) : xx = (x + x) :(xx) = (4) : 3 = 16/3

4) x + x = (x + 2xx + x) - 2xx = (x + x) - 2xx = ((x + x) - 2xx) - 2xx =( (4) - 2 3) - 6 = 10 -6 = 100 - 6 = 94