# In which interval the function #f(x)=sqrt(x^2+8)-x# is a decreasing function?

##### 1 Answer

Apr 4, 2017

#### Explanation:

Intervals of increasing of a function are those where

Here

and

#=x/sqrt(x^2+8)-1#

#=(x-sqrt(x^2+8))/sqrt(x^2+8)#

It is apparent that as

i.e. for all

Hence,

graph{sqrt(x^2+8)-x [-8.125, 11.875, -3.28, 6.72]}