Корни уравнений х(в квадрате)+mх+n=0 равны х1 и х2. Составьте квадратное уравнение ,корни...

$x^2+mx+n = 0\\\\ x_1, x_2\\\\ x_1 + x_2 = m\\\\ x_1*x_2 = n\\\\ y_1 = x_1/3, x_1 = y_1*3\\\\ y_2 = x_2/3, x_2 = y_2*3\\\\ y_1*3*y_2*3 = n\\\\ y_1*y_2 = n/9\\\\ y_1*3 + y_2*3 = -m\\\\ y_1+y_2 = -m/3\\\\ x^2+(m/3)x+n/9 = 0 | *9\\\\ 9x^2 + 3mx + n = 0$