Thank you for your kind review. Hearing that you were able to study this lecture easily makes me feel very rewarded. Also, because engineering mathematics has a vast amount of content, I think it would be difficult for me to create a lecture for it. (^ ^;) The lectures for engineering mathematics courses on other online university lecture sites are also made very easy and detailed. Therefore, if you complete this lecture to the end, I believe you will be able to easily study university calculus and engineering mathematics courses on other online university lecture sites as well.