Hi  Gautham,

The Joint Entrance Examination- Mains is held for admissions to  the various Undergraduate courses in the field of Engineering. Although it is true that NCERT forms the base of the JEE-Mains portion, it is nowhere close to the level of questions asked in the entrance examination, especially for Maths. It is  advised that you thoroughly understand the NCERT portion before moving on to the more advanced stuff that is asked in Mains.

You can check out our newly-launched B.Tech. companion to help yourself prepare for JEE-Mains 2020:

https://www.careers360.com/btech-companion