What are the local extrema of f(x)= 1/x-1/x^3+x^5-x?
1 Answer
Aug 21, 2017
There are no local extrema.
Explanation:
Local extrema could occur when
f(x)=x^-1-x^-3+x^5-x
f'(x)=-x^-2-(-3x^-4)+5x^4-1
Multiplying by
f'(x)=(-x^2+3+5x^8-x^4)/x^4=(5x^8-x^4-x^2+3)/x^4
Local extrema could occur when
f'(x) :
graph{(5x^8-x^4-x^2+3)/x^4 [-5, 5, -10.93, 55]}
We can check with a graph of
graph{x^-1-x^-3+x^5-x [-5, 5, -118.6, 152.4]}
No extrema!