(9a^2+3а+1)(3а-1) , при а =1/3
(9a^2+3а+1)(3а-1) = (9(1/3)^2+3*1/3+1)(3*1/3-1)= (9*1/9+3/3+1)(3/3-1)= (1+1+1)(1-1)= 3*0=0
(9a^2+3а+1)(3а-1) , при а =1/3
(9a^2+3а+1)(3а-1) = (9(1/3)^2+3*1/3+1)(3*1/3-1)= (9*1/9+3/3+1)(3/3-1)= (1+1+1)(1-1)= 3*0=0