We can't take backup of resource database but we can have backup of Data file and log file..
In SQL Server changes will only be made to the this database and will be reflected on all the system and user databases on the instance. If you need to apply a service pack on multiple instances, all you need to do is copy the Resource database's MDF and LDF files to the target instances. Rolling back the changes is as simple as overwriting the database files with an older copy. The physical file names of the Resource database are mssqlsystemresource.mdf and mssqlsystemresource.ldf and are located, by default, in <drive>:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data