@blackpenredpen is our very special guest for this collab! : ) Please sure you are subscribed to him if you are not already! Additionally he has the brilliant channel @bprpmathbasics where he has also explained plenty of A-level math questions as well and lots of interesting mathematics. If you need Physics Tutoring: The question he solves today is an integral from the Oxford Physics Admission Test the PAT. The original paper can be found here: Question 21 from PAT 2017: The question explores an integral and derivative with two different variables and explores the fundamental theorem of calculus. This question is great preparation for Oxford PAT for physics, engineering, Oxford MAT, and also preparation for A Level Maths, AP Math, IB Math and similar courses.