[求助] 以前的知识有点忘了，有谁能帮我证明下这两个函数的单调性？附问题

9楼: Originally posted by hank612 at 2013-11-08 00:29:32
x^2* Cos^2(theta) - (x- Sin^2(theta))
= (x-1) * Cos^2(theta) * (x- tan^2(theta)).

当0< theta <70, 那么 0< tan(theta) <tan(70 degree) = 2.747...,
所以 x * Cos(theta) - Sqrt( x - Si ...

3楼: Originally posted by feixiaolin at 2013-11-05 17:46:19
f(x)=|A/B|,
取A*B=0，得到几个点；
按照这几个点，划分成若干区间；
在各个区间内分别退去||符号、展开处理。