The second question, kAC=- 1=kPE, let p (m, 0), -4.
The third question, D (-2,0) has two cases, one is OD=DM, and the other is DM=OM. Firstly, calculate the AC expression, set the coordinates of m points, write two equations by using the equations of the two cases mentioned above, and then find the coordinates. There are three possible solutions?