Hey there

Calculus is the backbone of maths for jee. It is the longest part and has various important concepts as graph tracing which will help you in coordinate also. It gives you knowledge of functions. Calculus is very interesting at the same time if you don't understand it properly it will be a nightmare. I'll suggest you go with basics from Rd Sharma, then you can go to higher level books like cengage etc. You need to devote time for the subject if you want command in it. Regular revision is must otherwise you will forget the concepts.

Check our online learning platform it will help you in your JEE preparation

https://www.google.com/url?sa=t&source=web&rct=j&url=https://learn.careers360.com/knockout-jee-main-april/&ved=2ahUKEwi4sca20rLlAhUt6nMBHZKvBWAQFjAAegQIAhAB&usg=AOvVaw3XS9X1Sxkryg5E8liFJ_4C

Good luck