Hi

No, you are not eligible for btech, it doesn't matter even if you are overall passed.

This is because,

You have got RT i. e repeat in theory in your maths examination means you have failed in Maths.

But passing in maths is compulsory to be eligible for btech

For example,

Jee main is the most widely accepted

So, for your reference,

Jee main eligibility criteria is given below-

--------) Qualification required :- to be eligible  for JEE mains you need 10+2/equivalent qualification.

--------) Passing year :- one is eligible for JEE main examination for consecutive three years starting from the year of appearing for 12th /equivalent examination i. e to be eligible  for JEE mains 2022 you should be either appearing for 12th board exam or equivalent  in 2021 or should have passed it in 2020 or 2019

--------) There is no age limit to be eligible

--------) there is no minimum percentage requirement to be eligible for JEE Main.

But yes,

To be eligible for NITs, IIITs, CFTIs one needs at least 75% marks in class 12th if belongs to General or OBC category  or at least 65% marks in class 12th if belongs to Sc or St category. For this year i. e 2021 this minimum percentage requirement of 75% - 65 % has been lifted off.

For detailed information about jee main eligibility criteria  go through our page, the link for which is provided below

https://engineering.careers360.com/articles/jee-main-eligibility-criteria

But yes,

There are some colleges like VIT which offer btech biotechnology to biology students, so in case, if you have biology in your 10+2 then you can still go for btech biology even though you have failed in maths and are overall passed .

Thank you