Why do you assume you can not?
Here is a how to:
Now first thing you need to do is to create partition for Ubuntu. Open run and type “diskmgmt.msc” there and hit enter. Now right click on the partition where you want Linux to be installed and select “Shrink Volume”. Select the size of the partition and click on “Shrink” button.
Now since you have created a partition for Ubuntu, we are all set to start the installation of Ubuntu on this hard drive partition. Restart your computer and then boot it from USB Flash drive or DVD (on which you have mounted the Ubuntu ISO).
When your computer is successfully booted from installation media, click on “Install Ubuntu”. On next Window, select “Something Else” Option. Next select the partition you have created for Ubuntu and let the installation begin. Once the installation is completed, your computer will restart. Restart your computer and you will be asked for whether you want to boot into Windows 8 or Ubuntu.
This was simple guide related to dual boot Windows 8/8.1 & Ubuntu. If we missed any step or you are having difficulty achieving the required results, then let us know.
This how to assumes you know about this: GRUB UEFI windows boot fail. Disable Secure Boot. And in case you never created a dual boot before: your BIOS needs to be set to boot from CD/DVD/USB as your first boot device, after install you can change it back.