а) D = 121 + 168 = 289
x1 = (11 + 17) / 2 = 14
x2 = (11 - 17) / 2 = - 6 / 2 = -3
б) x^4 - 13x^2 + 36 = 0
x^2 = t
t^2 - 13t + 36 = 0
D = 169 - 144 = 25
t1 = (13 + 5)/2 = 9
t2 = (13 - 5)/2 = 8/2 = 4
x1 = 81 x2=16
в) -2x^2-5x-2 = 0 Умножим левую и правую часть на -1
Получаем 2x^2+5x+2=0 (для простоты нахождения D)
D= 25 - 16 = 9
x1 = (-5 + 3)/4 = -2/4 = -0,5
х2 = (-8)/4 = -2