导数的乘法法则推倒uv)'=lim(h→0)[u(x+h)v(x+h)-uv]/h=lim(h→0)[u(x+h)v(x+h)+u(x+h)v-u(x+h)v-uv]/h=lim(h→0)[u(x+h)]×[v(x+h)-v(x)]/h+lim(h→0)[v(x)]×[u(x+h)-u(x)]/h=u(x)v'(x)+u'(x)v(x)=u'v+uv'请问这个第一步lim(h→0)[u(x+h)v(x+h)-
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导数的乘法法则推倒uv)'=lim(h→0)[u(x+h)v(x+h)-uv]/h=lim(h→0)[u(x+h)v(x+h)+u(x+h)v-u(x+h)v-uv]/h=lim(h→0)[u(x+h)]×[v(x+h)-v(x)]/h+lim(h→0)[v(x)]×[u(x+h)-u(x)]/h=u(x)v'(x)+u'(x)v(x)=u'v+uv'请问这个第一步lim(h→0)[u(x+h)v(x+h)-
导数的乘法法则推倒
uv)'=lim(h→0)[u(x+h)v(x+h)-uv]/h
=lim(h→0)[u(x+h)v(x+h)+u(x+h)v-u(x+h)v-uv]/h
=lim(h→0)[u(x+h)]×[v(x+h)-v(x)]/h+lim(h→0)[v(x)]×[u(x+h)-u(x)]/h
=u(x)v'(x)+u'(x)v(x)
=u'v+uv'请问这个第一步lim(h→0)[u(x+h)v(x+h)-uv]/h 是怎么来的
我算出来的的第一步是
[u(x+h)-u(x)]/h*[v(x+h)-v(x)]/h
=u(x+h)v(x+h)-u(x+h)v(x)-u(x)v(x+h)+u(x)v(x)/h*h
然后呢 因为h->0就消掉么?
导数的乘法法则推倒uv)'=lim(h→0)[u(x+h)v(x+h)-uv]/h=lim(h→0)[u(x+h)v(x+h)+u(x+h)v-u(x+h)v-uv]/h=lim(h→0)[u(x+h)]×[v(x+h)-v(x)]/h+lim(h→0)[v(x)]×[u(x+h)-u(x)]/h=u(x)v'(x)+u'(x)v(x)=u'v+uv'请问这个第一步lim(h→0)[u(x+h)v(x+h)-
首先,如果要取极限h→0,那么所有的h都要取极限,所以不是因为h→0而消掉的.这是求极限很容易犯得错误.
其次,第一步是来自y‘=△y/△x.令y=u(x)v(x),则△y=u(x+h)v(x+h)-u(x)v(X),再将△y带入△y/△x,其中△x=h,即得到第一步.
最后,楼主算的第一步是错的,[u(x+h)-u(x)]/h=u',[v(x+h)-v(x)]/h=v'.也就是楼主算的第一步中自己默认了y‘=u'*v',这个公式本身就是错的.
自己码的好辛苦啊,中途浏览器还崩坏了一次,╮(╯▽╰)╭好累,感觉不会再爱了.
[u(x+h)v(x+h)+u(x+h)v-u(x+h)v-uv]/h
= [u(x + h)v - uv]/h + [u(x + h)v(x + h) - u(x + h)v]/h
= v[u(x + h) - u]/h + u(x + h)[v(x + h) - v]/h