2 9 - a - 3*a
9 - a^2 - 3*a при a = 1/3
9 - a^2 - 3*a
9 - (1/3)^2 - 3*(1/3)
9 - (1/3)^2 - 3/3
71/9
9.0 - a^2 - 3.0*a