SImply look up the service manual -- it will tell you what's inside without needing to open up the system. [URL]   Or, go ahead and look inside if you won't be convinced any other way despite being told the facts.    
I have a Dell Inspiron 3542. When I bought this laptop, there was no graphics card, and I am running on the integrated graphics. But on the Dell support website, in the driver section, if I DISABLE "show downloads only for this PC", without entering the service tag, it also shows me a Nvidia GT840M / 820M / 920M graphics driver. So that means one of these graphics cards were available when purchasing this laptop. Today, I am thinking about upgrading this laptop. So does that mean I have a slot and space for one of these graphics cards in my laptop? I haven't yet opened my laptop so I can't see.
Does my laptop support a graphics card?