We have,

Now by using middle-term splitting, we get

= 1/3 x² – 3x + x – 9

= x (x/3 – 3) + (x – 9)

= x/3 (x – 9) + 1 (x – 9)

= (x – 9) (x/3 + 1)

= (x – 9) × (x – 3)/3

= 1/3 (x – 9) (x + 3)

Hence,

The given expression can be factorized as: