求y=arctanx+arctan(1-x)/(1+x)的值x∈(-无穷,-1)∪(-1,+无穷)tany=tan(arctanx+arctan(1-x)/(1+x))=1∵x≠-1,(1-x)/(1+x)≠-1,arctanx∈(-π/2,-π/4)∪(-π/4,π/2),arctan(1-x)/(1+x)∈(-π/2,-π/4)∪(-π/4,π/2) ,又∵tany=1,∴y=π

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求y=arctanx+arctan(1-x)/(1+x)的值x∈(-无穷,-1)∪(-1,+无穷)tany=tan(arctanx+arctan(1-x)/(1+x))=1∵x≠-1,(1-x)/(1+x)≠-1,arctanx∈(-π/2,-π/4)∪(-π/4,π/2),arctan(1-x)/(1+x)∈(-π/2,-π/4)∪(-π/4,π/2) ,又∵tany=1,∴y=π
求y=arctanx+arctan(1-x)/(1+x)的值
x∈(-无穷,-1)∪(-1,+无穷)
tany=tan(arctanx+arctan(1-x)/(1+x))=1
∵x≠-1,(1-x)/(1+x)≠-1,arctanx∈(-π/2,-π/4)∪(-π/4,π/2),arctan(1-x)/(1+x)∈(-π/2,-π/4)∪(-π/4,π/2) ,
又∵tany=1,
∴y=π/4或-3π/4.
最后一步不太懂.为什么会分两类呢
当x>-1时,y=π/4;当x<-1时,y=3π/4.

求y=arctanx+arctan(1-x)/(1+x)的值x∈(-无穷,-1)∪(-1,+无穷)tany=tan(arctanx+arctan(1-x)/(1+x))=1∵x≠-1,(1-x)/(1+x)≠-1,arctanx∈(-π/2,-π/4)∪(-π/4,π/2),arctan(1-x)/(1+x)∈(-π/2,-π/4)∪(-π/4,π/2) ,又∵tany=1,∴y=π
tany=1 y可以有无穷多个值 但是前面几步(arctanx∈(-π/2,-π/4)∪(-π/4,π/2),arctan(1-x)/(1+x)∈(-π/2,-π/4)∪(-π/4,π/2) ) 限制y大于-π 小于π y就只能是π/4或-3π/4
但这里答案省略arctanx∈(-π/2,-π/4)和arctan(1-x)/(1+x)∈(-π/2,-π/4)对应x<-1
arctanx∈(-π/4,π/2)和arctan(1-x)/(1+x)∈(-π/4,π/2) 对应x>-1
这样就清楚了吧?

x小于-1时,arctanx和arctan(1-x)/(1+x)都是负的,所以y要取负值