# Is #f(x)=1/x-1/x^3+1/x^5# increasing or decreasing at #x=-1#?

##### 1 Answer

Feb 4, 2017

Decreasing.

#### Explanation:

Rewrite

#f(x) = x^-1 - x^-3 + x^-5#

Differentiate:

#f'(x) = -x^-2 - (-3x^-4) - 5x^-6#

#f'(x) = -1/x^2 + 3/x^4 - 5/x^6#

Let

#f'(-1) = -1/1^2 +3/1^4 - 5/1^6 = -1 + 3 - 5 = -3#

Hence,

Hopefully this helps!