I failed in 12th this year from 3-marks in maths, how can I now I become an ethical hacker or from where can I study?

You failed in Maths is completely different from your interest and choices. Hacking requires good aptitude and stimulation skills too. Take my advice, try your best and go for some computer Science degree with certifications from reputed brands. Next is YouTube and Google are initial helpers but not

If u are good learner then u can take help through you tube and both maths and hacking is different field.