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installing ubuntu alognside windows using manual partition 
have a partitions of free space of 85 gb i want to use for it
how do i go about it
i doing manual partion cos i have bit locker enabled and i cant disable it cos its a work laptop
i want to automaitcally boot to windows
and to boot to ubuntu only when going to booti options in the laptop and selecting
this is a dell precisions laptop
i dont see an efi partition
there is an vfat partion system label windows boot manager
also do i need to bitlocker recovery key, what if i cant get it