In JEE MAIN 2019 of both Jan and April exam, from which topics the questions asked are tough in Maths
For knowing the detailed analysis of difficulties of jEE mains paper 2019 you Can refer to the link below.
https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-analysis/amp
Hello aspirant, in JEE mains 2019 the toughest questions that was asked from maths were from coordinate geometry topic.
All the best for your preparation.
Hope this may help you