The formula of high number is the basis and top priority of postgraduate entrance examination and science and engineering research. Mastering these formulas can help candidates learn advanced mathematics knowledge quickly.
Limit: Let the function f(x) have a definition in the centripetal neighborhood of point X. If there is a constant A, there is always a positive number δ for any given positive number ε (no matter how small it is), so that when x satisfies inequality 0.