See in most of the boards, the 10+2 boards results are given in terms of best of 5. Now if your board declares pass if a student pass atleast in 5 subjects then yeah your aggregate will be made based on the 5 subjects you have passed in. Although I would say if you want to go for higher degrees or for any job exams then you should clear your backlog even if you are marked passed in order to be safe.

**Your answer is relevant to your board. I would say if you can consult this with your school teacher, he/she will give you the rules based on your boards.

I hope this answer helps. All the very best for your future endeavors!