So the axis of symmetry is on the right of point p.

Parabola should be an axisymmetric figure.

P(- 1，2b)，BP=2PA。

So B(-3, -2b) -b- 1\2=-2.

So b=5.

There should be b+c=-2, so c=-7.

So the quadratic function relation corresponding to parabola is y=x2+4x-7.

Gee, I'm very tired. Plus points ~ ~

Hu roared ~