How Can I Write Math Formulas in a PDF Document?

How can I write math formulas in a PDF document? I want to add some math formulas into my notes in PDF.

Hi there!! Maths is a very interesting subject, one gets easily engrossed in it once t catch the flow. But when it comes to revising the sum you did earlier than it could be a totally annoying, cuz one starts feeling bored and irritated from doing the same thing again and again but if you just neglect that then believe me you are gonna end up in a huge trouble while your examination. Therefore here are some tactics which you could follow while revising.- Take a sheet of paper and write down all the formulas chapterwise, no matter how big or small t are.And remember to go through them regularly so that t are learned by heart. Now take the text book of your school and go through all the concepts very nicely. And if supposedly you couldn't understand the writings of your text book then you can refer any good reference books where the concepts are explained properly. Try out the solved examples to recall the way of solving a particular sum and then you can possibly go for exercises on your own. This will thrill you and also let you explore your capabilities. Solve practice papers and previous year questions. For making study more fun you can ask your friends to prepare a set of questions which t find difficult and then you could try solving them. This will increase your confidence and also you would remembering that sum while your examination because who knows you might be lucky enough to get one of those. So this was all. I hope it will prove helpful to you. All the best!!