[ubuntu] Asus X550VC & Intel HD4000 & nVidia GeForce 720m

Hello. I am trying to get this configuration to work for 2 days already without success.

So, I want to start from begiing if someone is willing to write me the steps and say what I need to do, in correct order, to get it to work.

Laptop Model: ASUS X550VC
Graphics Card #1: Intel HD4000
Graphics Card #2: nVidia GeForce 720m, which supports CUDA, Optimus, PhysX, etc

Also, you should know that installing nVidia drivers in Additional Drivers is not working as Ubuntu crashes after reboot.
I got to do installation using command line. I would really use some help with this.

Does anyone can write a small tutorial for me?

Thank you in advance!
Dale