Mathematics is a beautiful and interesting branch of study. However, many students unnecessarily have a phobia about it. My effort in this book has been to present the theory, examples and questions in a coherent and well-knit manner, not only encourage the students to learn and understand the subject but also provide an insight into its beauty. However, the students are advised not to read this book like a storybook- they should sit with a pencil an notepad, and whenever during theory or examples, we say, Please do it!, it is necessary that the students do those steps. The entire matter is given in a logical sequence so as to develop and strengthen the concepts. Ultimately conceptual clarity is what is needed for success in any examination-be it CBSE or IIT JEE or any other competitive examination. I have been invited as a resource person in a number of workshops organized by various government agencies and my publishers. In these workshops I get opportunity to interact with the teachers. many teachers gave a number of valuable suggestions. I also receive lot of letters and e-mails from teachers, parents and students -full of suggestions, criticism and queries. Based on this feedback, the book has been thoroughly revised and new feature -Illustrative examples for Multiple Choice Questions has been added. The questions of NCERT Exemplar Problems, Multiple Choice, Very Short Answer, Short Answer and Long Answer Questions have been included. Assertion-Reason Type and Case-Based/Source-based Questions are also included. I hope that teachers and students will be fully satisfied with this edition, and it will meet their needs and expectations.