a) The function is decreasing in [-3, -1)
b) The function is negative in (-3, 1)
Where is the function negative?
The graph of the quadratic equation is in the image at the end.
Remember that:
A function decreases if, when reading from left to right, the graph goes downwards.
A function is increasing if, when reading from left to right, it goes up.
On the interval [-3, -1) we can see that the graph goes down, so it is decreasing.
And the function is negative if the graph is below the horizontal axis, we can see that the the graph is below the horizontal axis in the interval (-3, 1)