Hey,

I would personally recommend books of author R.D. Sharma, R.S. Agarwal.

Both these books are available for 11 and 12 standard as well as useful for competitive exams and various entrance exama.

Theory given in these books is written as to understand easily and there are many solved examples to understand the concepts.

There are various types of numericals to solve which will help you practice a lot.

Thank You.