thanks all~~~
圖片參考:http://imgcld.yimg.com/8/n/HA07941386/o/701202040100413873434660.jpg
更新1:
http://www.hkeaa.edu.hk/DocLibrary/HKDSE/Subject_Information/math/SamplePaper-MATH-Compulsory-Paper1-C.pdf 第17題