换无法则对简化定积分计算的优越性和必要性

Advantage and Necessity of Altering Variate Law in Simplifying Definite Integral Calculation

以牛顿———莱布尼兹公式为依据，根据不定积分求原函数的过程，再加上正确处理好积分的区间。

In this paper,advantage and necessity of altering variate law is emphasized.willbe obtained by means of working out integrand's original function with in definite integral calculus,useing Newton Leibniz's formula,and paying attention to integral domain.