Learn Finnish: Oletko liian laiska hinnoitellaksesi tämän käytetyn television? - Are you too lazy to price this used television?

This is the core of the excessive resultative construction you are learning. It is built from the first infinitive of the verb hinnoitella (to price), plus the translative case ending -kse, and finally the second-person singular possessive suffix -si. Together with liian laiska, it forms the meaning 'too lazy to price'.

Why does hinnoitellaksesi use the -si possessive suffix instead of -nsa?

In this construction, the possessive suffix attached to the infinitive must match the subject of the sentence. Since the subject is 'you' (indicated by the verb oletko), the suffix must be the second-person -si. If the sentence were about someone else being too lazy, it would be hinnoitellakseen.

Why are the words tämän käytetyn television in the genitive-looking accusative case instead of the partitive?

The verb hinnoitella (to price) takes a total object here because pricing a specific television is viewed as a complete action. Since the sentence is not negative (even though it is a question) and has a standard subject, the whole object phrase takes the -n ending.

The word käytetyn means 'used'. What verb form is this?