The function is , .

Find the critical numbers by applying derivative .

Equate it to zero .

For .

.

For .

.

Therefore the critical numbers are and in the interval .

Therefore the function have only one test interval .

Test intervals	\ Test value \	\ sign of \	conclusion
		\ \	Decreasing

The function  is decreasing on the entire interval .

The function  is decreasing on the entire interval .