The equation of parabola is

For point (-1,-9), equation of parabola is

For point (1,7), equation of parabola is

For point (-6,-14), equation of parabola is

So we have three equations , which are

Subtracting first two equation will give

Subtracting second and third equation gives

Substituting 8 for b, we will get

back substituting 8 for b and 1 for a, we will get

So we have

Therefore required equation is
