em xem hướng dẫn gõ công thức ở đây nhé https://diendan.hocmai.vn/threads/cach-go-cong-thuc-toan-hoc-vat-li-hoa-hoc-forum-moi.603868/
https://diendan.hocmai.vn/threads/cach-go-cong-thuc-toan-hoc-vat-li-hoa-hoc-forum-moi.603868/