We know that
So, we can see that g(x) is f(x) reflected in the x-axis. But, it has another change which is a downward movement in 3 units.
So, we can deduce that
Sketch of the situation:
When you reflect f(x) in the x-axis, you obtain something like -f(x).
We can see that -f(x) intersect the y-axis in -1. But, g(x) intersect the y-axis in -4.
So, we need to move the function 3 units down. Whe we make the movement the graph will intersect the y-axis in -4 because -1-3=-4.