Решите уравнения x^2=-x+20 пож
Х^2 = -x+20 x^2+x-20=0 D=b^2-4ac = 1-4*1*(-20)=1+80=81 x(1,2) = (-b+-√D)/2a = (-1+-9) / 2 x(1) = (-1-9)/2 = -10 / 2 = -5 x(2) = (-1+9) / 2 = 8/2 = 4