Mathematics is a imaginary world of number,This subject is fully involves observation and its problem can be solved by observing various types of pattern and some times we can't conclude a pattern then we have to find some another way to get that.
For e.g Sir RAMANUJAN the great mathematician who discovered sum of all infinite natural number,I am giving this example because i know a person who know some basics of maths can even be able to say that it should be a positive real number but they give it's sum is -1/12 , so this I meant to say.
Story begins now✓
In 1960 a examination is held in INDIA called IIT JEE ,this examination is taken to find best engineers across the country (India) .after 1960 IIT JEE exam is taken every year and it is now the world second toughest exam , first is GAOKAO , for this type of exams we need a good book for preparation so finally we found one of them Which is Cengage of G.Tewani sir (calculas,coordinate geometry,vectors and 3d geometry,algebra, trigonometry), it is a good book with good level of questions .
Disclaimer -THIS ONLY ABOUT MATHEMATICS SECTION ASK'S IN IIT JEE NOT FOR ANOTHER 2 SECTION THEIR AUTHORS ARE DIFFERENT ,THIS ARTICLE DOESN'T CONTAIN ANY HATE ABOUT SOME ONE.