Dear student, an attempt has been made to understand this book through a very simple method, the purpose of writing this book is for all those students or teachers who can teach students through the simplest method. 

Efforts have been made to make all the topics as simple as possible, the use of this book is not limit to polytechnic engineering, as well as for those students who are studying these topics, they can also use it on their subject 

It has been written keeping in mind the main point of the book so that the students can use it as much as possible, I want to thank my publication who made the book in the right way by which I am sure that it will be able to give more help to the students.