Can I increase my Dell laptop from 2 cores to 4 cores? I want to use it to play videogames on it. How can I get to do this? I have a Dell Inspiron 15 5000
Yes, you can if the processor is upgradable. Then all you need to do is, find a compatible replacement which has 4 cores. But some laptops have nonreplaceable, soldered-in CPUs. In that case, it is designed not to be upgradable. Therefore, you can't upgrade. (Technically, you can if you are an expert but it is not recommended and it just not worth it.)
However, if you want to play video games, then you should more concern about the GPU. Just for the record, in most laptops, you can't upgrade the GPU.