How can Linux/Ubuntu be installed safely on ChromeBook? [closed]

Chrubuntu is a true dual boot and loads that way. Chrubuntu no longer works and will not be updated. It's potentially dangerous to install Chrubuntu on Chromebooks with newer models of Intel processors.

Crouton runs side by side with Chrome OS. Crouton is the better choice if you're not familiar with Ubuntu and just need a separate OS to launch some apps you need. You can run a music player app like Rhythmbox in Crouton and then switch back to ChromeOS in a matter of seconds for quick seamless browsing while it plays. Crouton also has less potential problems with glitchy device drivers for Chromebook hardware than Chrubuntu.

chrx is a currently maintained project for dual booting various Linux distributions alongside ChromeOS. The default distribution is GalliumOS. GalliumOS is derived from Xubuntu and developed specifically for compatibility and optimized performance on Chromebook hardware. The downside of chrx is that it doesn't support ARM processors and firmware updates are required or recommended for newer models of Intel processors, so it's also more dangerous than Crouton.