2 3*a*b + a
(3*a)*b + a^2 при a = 1/3
(3*a)*b + a^2
(3*(1/3))*b + (1/3)^2
(3/3)*b + (1/3)^2
1/9 + b
a^2 + 3.0*a*b
a*(a + 3*b)