(1) If the title gives a chord with a midpoint of O(x, y), the equation of this chord can be found. The solution is as follows: Let this chord intersect with the curve at points A(a, b) and B(c, d), then O is the midpoint of A and B, and 2x = a..

b，2y=c

D, the chord slope is K=(b-d)/(a-c)=y/x, so the chord equation is Y-y=K(X-x). (2) Generally, it can be solved according to the topic conditions.

parabolic equation

1, if the parabola opens to the right, it is Y =2px, and the focus is (p/2,0) 2. If the parabola opens to the left, it is Y =-2px and the focus is (-p/2,0).