Translation of "to prove" into Portuguese

I was trying to prove something.

Eu estava a tentar de comprovar algo.

He had proved what he needed to prove, to himself and anyone who doubted him.

Tinha mostrado o que precisava mostrar, a si mesmo e a todos aqueles que duvidavam dele.

It's very unlikely that any evidence will turn up to prove Tom's guilt.

É muito improvável que surja alguma evidência que prove a culpa do Tom.