So I have a PC and a laptop, but I don't have a monitor for the PC, now I thought maybe. Can you connect the laptop to the PC that I use the laptop as a single monitor for the PC? To make a screen extension out of the laptop.
I want to use the technology so the pc's processor and graphics card because they have more power than my laptop
There are various programs for this, the Team Viewer is also quite common.
Yes, that should work. It may well be that there's a certain latency. Otherwise you could possibly use a capture card or, if your GPU supports it, stream with it somehow. At Nvidia there's e.g. Shadowplay, I think AMD also has something comparable. Nvidia Shield can also do something, there's also a desktop program that you can use instead of the tablet, at least for Linux.
On YouTube I only find descriptions of how to…
you can't find anything else either, because there's no solution for your project. It just does not work.
As Kenshin said it works. But let's be honest, get yourself a monitor. This will make you happier.
If I could afford it…