try to convince him
Provavelmente não vale a pena tentar convencê-lo.
It’s probably not worth trying to convince him.
Ela estava cansada de tentar convencê-lo.
She was tired of trying to convince him.
Provavelmente não adianta tentar convencê-lo.
It’s probably no use trying to convince him.
Você está perdendo seu tempo a tentar convencê-lo.
You’re wasting your time trying to convince him.