Answer:
( -∞, -3 ) or any subinterval of ( -∞, -3 )
Step-by-step explanation:
h(t)=(t+3)^2+5 has the form
h(t) =(t-h)^2 + 5, indicating that h(t)=(t+3)^2+5 represents a parabola with vertex at (-3,5) that opens up. This (-3,5) is the minimum point of the graph.
To the left of t = -3, h(t) is decreasing; to the right of t = -3, h(t) is increasing.
Thus, it is on any interval to the left of t = -3 that the rate of change of this function is negative (the function is decreasing on ( -∞, -3 ).