Must a function that is decreasing over a given interval always be negative over that same interval? Explain.

Clearly, this function is decreasing and negative (i.e. below the x-axis) over its domain. ... Therefore, a function need not be negative over the interval it is decreasing on.

Explanation:

For a function to be decreasing over an interval, the outputs are getting smaller as the inputs of the function are getting larger.  

The outputs of a decreasing interval could be positive or negative.  

For a function to be negative over an interval, the outputs must be negative, while the inputs could be positive or negative.

Explanation:

thats all you need.