I just got my Inspiron 15 3000 Laptop as an upgrade to my Inspiron 15R 5537.
My question js this: I have in my previous Inspiron 4 GB RAM (DUAL IN-LINE MEMORY MODULE, 4GB, 1600, 2RX8, 2G, DDR3L, S), and I'd like to add it to my new laptop, which has a 2GB and a 4GB, so basically, removing the 2GB and outting in the 4GB from the 5537.
It depends on the processor you purchased and the exact model system. If it's the newest generation of CPUs (seventh generation Kaby Lake) it requires DDR4 and the DDR3 from the old system will not work.
If it's a model that uses an older-generation CPU, the DDR3L you now have should work.