we are given with two points of a parabola : v (5,-1) and f (3,-1). In this case, we can see that the parabola is opening to the left which means the standard form to be followed is -4a(x-h) = (y-k)^2. a is equal to 2. substituting, -4*2 (x-5) =(y+1)^2. This is equal to -8 (x-5) = (y+1)^2