(x-y)d(ln(x-y))为什么等于dx-dy?看不懂T^T!
问题描述:
(x-y)d(ln(x-y))为什么等于dx-dy?看不懂T^T!
答
(x-y)d(ln(x-y))
=(x-y)*1/(x-y)*d(x-y)
=d(x-y)
=dx-dy