Let us put g(x) in the vertex form at first
[tex]g(x)=-3(x-0)^2-5[/tex]-3 means the graph of f(x) stretched vertically by a scale factor 3 and also reflected across the x-axis
-5 means the graph of f(x) is translated down by 5 units
Then f(x) is stretched vertically by a scale factor 3, reflected across the x-axis and translated 5 units down