PostgreSQL: change date by the random number of days

Question

How can I change the date by the random number of days in PostgreSQL?

Unfortunately Generate a random number in the range 1 - 10 solution with trunc doesn't work:

select date(now()) + (trunc(random()  * 20)) 

results in:

ERROR:  operator does not exist: date + double precision
LÍNEA 1: select date(now()) + (trunc(random()  * 20))