lim _(n->； ∞) n [f(a+2/n)-f(a)]

= 2 lim _(n-& gt； ∞) [f(a+2/n)-f(a)] / (2/n)

Let h=2/n

= 2 lim _(h-& gt； 0) [f(a+h)-f(a)] /h

=2 feet (a)

lim _(h-& gt； 0) [f(a+nh)-f(a-mh)] /h

= lim _(h-& gt； 0)[(f(a)+nh*f'(a)+o(h^2))-(f(a)-mh*f'(a)+o(h^2))]/h

=(n-m)

Curriculum characteristics

Generally speaking, advanced mathematics is a basic subject formed by calculus, algebra, geometry and their intersection after17th century. Compared with elementary mathematics and secondary mathematics, mathematics is more difficult to learn, so it is often called "advanced mathematics" and "calculus" in textbooks, which is a different major of science and engineering. Students majoring in literature and history learn mathematics shallowly, and different majors in literature and history have different depths.