dell inspiron 15 sesries have dedicated graphic slots

[sulo1993]

if dell inspiron 15 i3 3rd generation laptop has dedicated graphic slots

 

[Phillip Corcoran]

It doesn't have any open graphics slot, it's already occupied by an AMD Radeon discrete card, plus another graphics chip integrated in to the Intel i3 processor. They can be switched from one to the other according to your configuration based on the graphics power required for a particular application or game.

The laptop defaults to using the Intel GPU for running the Windows shell & basic tasks.

The Intel GPU has no dedicated memory - - it uses a portion of system RAM.
The AMD Radeon GPU does have it's own dedicated memory.