In the limit of higher mathematics method, the method of using equivalent infinity substitution limit is rarely mentioned, using the equivalent infinity substitution limit and equivalent infinitesimal substitution limit can have the effect of simplified calculation. In substitution for the product factor can be equivalent infinity substitution, but under certain conditions can also be used to limit the type of the product factor equivalent infinity substitution limit.来自有道翻译 In the limit of higher mathematics method, the method of using equivalent infinity substitution limit is rarely mentioned, using the equivalent infinity substitution limit and equivalent infinitesimal substitution limit can have the effect of simplified calculation. In substitution for the product factor can be equivalent infinity substitution, but under certain conditions can also be used to limit the type of the product factor equivalent infinity substitution limit.来自有道翻译