It is known that the straight line y = - 2x + B, B is not equal to 0, intersects with X axis at point B; the analytic formula of a parabola is y = x square - [B + 10] x + C 1. If the parabola passes through point B and its vertex P is on the straight line y = - 2x + B, try to determine the analytical formula of the parabola; If the symmetric axis of the parabola just passes through point C, try to determine the analytical formula of the straight line y = - 2x + B!

It is known that the straight line y = - 2x + B, B is not equal to 0, intersects with X axis at point B; the analytic formula of a parabola is y = x square - [B + 10] x + C 1. If the parabola passes through point B and its vertex P is on the straight line y = - 2x + B, try to determine the analytical formula of the parabola; If the symmetric axis of the parabola just passes through point C, try to determine the analytical formula of the straight line y = - 2x + B!

1. If the parabola passes through point B, then B = C, the parabola equation becomes y = x & sup2; - (B + 10) x + B, and the vertex coordinates (B / 2 + 5, - B & sup2 / / 4-4b-25) are on the straight line y = - 2x + B, that is - B & sup2 / / 4-4b-25 = - B-10 + B,
By solving the equation B & sup2; + 16b + 60, B = - 10 or B = - 6
So the analytic formula of parabola is y = x & sup2; - 10 or y = x & sup2; - 4x-6
2. Where is point a?