hello,

I am studying the integral test at the moment and I understand that in order to be able to use the integral tests on series to find whether they converge or diverge is by making sure that the function is continuous, positive and decreasing.

I am having problem with proving that the function is decreasing...

for example i got the following problem:

I know that I could use something called the first derivative test which requires me to take the derivative of the function and then find the critical points but I am not sure how that can help me prove that the function decreases... Any help would be greatly appreciated.

thank you.