hello, i use ubuntu mate on my raspberry pi 3 and i installed it on a sd card but i cant made the system updates because of no space in /root. How can i expand the /root partition?
I do not own one, but this question comes up often. Maybe have a look here until raspberry help shows up. Good luck 
Have you tried going to the welcome screen and clicked on “Raspberry Pi Information” and click the resize partiton button? 
Hope this worked!