It is difficult but if you have the determination and put a lot of efforts I believe you can pass it. These 3 papers will held continuously so make sure you are in good condition to take these 3.
taking all 3 core papers one shot is disaster!
unless u had been consistently doin ur study work throughout the semester.
so far, i've only known a few seniors that successfully cleared all 3 core papers 1st attempt.
so all da best dude