Решите уравнение (х-3)2+9(х-3)+20=0

Пусть x - 3 = t t^2 + 9t + 20 = 0  D= 81 - 80 = 1 t1 = ( - 9 + 1)/2 = - 8/2 = - 4; t2 = ( - 9 -  1)/2 = - 10/2 = - 5; x - 3 = - 4 x = - 1 x - 3 = - 5 x = - 2