Given vertex (3 , -6)and focus (3 , -4) of a parabola

The focus is directly below the vertex, indicating a down-opening parabola

Vertex is (h , k) = (3 , -6)

Focus is (h , k-p) = (3 , -4)

==> k-p =-4

==> -6-p = -4

==> -p = -4+6

==> -p = 2

==> p = -2

==> 4p = 4(-2)

==> 4p = -8

Equation of parabola is

We know vertex is (3 , -6) and 4p = -8