hi,

see I assume you are asking about jeevanson publications mathematics books, jeevanson has applied mathematics books for class 11 and 12th standard. as per students review the books is quite helpful for understand the theory paper and have lots of solved questions. however I also suggest you to follow ncert also since it syllabus is standard and have the syllabus according to jee main like entrance test. since 12th mathematics is quite hard it is always good to follow two books and solve questions by your own as much as possible.