Решите уравнение х2-18х+21=0

х^2-18х+21=0 D = (-18)^2 - 4*1*21 = 324 - 84 = 240V240 = V16*15 = 4V15x1 = 18 + 4V15 / 2 = 9+2V15x1 = 18 - 4V15 / 2 = 9 - 2V15