Question 878178
This response assumes that the vertices you report are the correct one for each equation.


You would rely on knowledge of the standard form equation for a parabola.
{{{y=a(x-h)^2+k}}} has vertex (h,k).  The transformation between general and standard forms would not change to "a" variable.  This will be the same variable or number as found on the leading term of general form.


{{{y=-2x^2+16x-27}}}, if vertex (4,5) should be {{{y=-2(x-4)^2+5}}};


{{{y=4x^2+8x+1}}}, if vertex (-1,-3) should be {{{y=4(x+1)^2-3}}}.