It is known that line L and parabola C1: y = - X2, C2: y = - x2 + ax are tangent to points a and B respectively, and Given that the line L is tangent to the parabola C1: y = - X2, C2: y = - x2 + ax respectively, and points a, B, "ab" = 3 root sign, 5 divided by 4, find the value of A

It is known that line L and parabola C1: y = - X2, C2: y = - x2 + ax are tangent to points a and B respectively, and Given that the line L is tangent to the parabola C1: y = - X2, C2: y = - x2 + ax respectively, and points a, B, "ab" = 3 root sign, 5 divided by 4, find the value of A

Let the equation of the line l be y = KX + B, and let the coordinates of tangent points a and B of L and C1, C2 be (x1, Y1), (X2, Y2) respectively, then X1 and Y1 must be the equations of L and C1, C2, respectively. The only real root of the univariate quadratic equation about X obtained by simultaneous elimination of Y is the equation of L and C1