Yesterday, in the market in a shop they have shown me a laptop and said it constitutes 4gb integrated gpu with i5 7g and also has a dedicated gpu of 2gb amd radeon. So, is it possible to have both integrated and dedicated gpu in a same platform?
Basically all mobile (laptop) Intel CPUs have an integrated graphics core. The brand name (Dell, Asus, Lenovo, etc.) may decide to include a dedicated GPU chip in a specific laptop model.
The integrated GPU uses some of the system for itself. I think Intel HD graphic cores can use up to 2GB of system RAM, assuming the laptop has enough system RAM for Windows to assign to the Intel HD based on demand. However, laptops can be designed to limit how much RAM the Intel HD can actually access no matter how much system RAM the laptop has.
Laptops with both Intel HD integrated and dedicated GPUs can only use one of them at a time. They cannot be combined to provide better performance.