lnarctan1/1+x x+1是分母哦,求导.
问题描述：
lnarctan1/1+x x+1是分母哦,求导.
答
(lnarctan1/(x+1)
=1/arctan1/(x+1) * [arctan1/(x+1)]'
=1/arctan1/(x+1)*[1/(1+(1/(x+1))^2]*(1/(x+1)'
=1/arctan1/(x+1)*(x+1)^2/[(x+1)^2+1]*[-1/(x+1)^2]
=-1/{[(x+1)^2+1]*arctan1/(x+1)}[-1/(x+1)^2的分母在最后的答案中哪里去了？？麻烦告诉下谢了约分约掉了。1/arctan1/(x+1)*(x+1)^2/[(x+1)^2+1]*[-1/(x+1)^2]- ------ ---------- 分子分母