What are the local extrema of f(x)= ((x-2)(x-4)^3)/(x^2-2)f(x)=(x2)(x4)3x22?

1 Answer
Aug 20, 2017

X=-5X=5

Explanation:

f(x)=[(x-2)(x-4)^3]/(x^2-2)f(x)=(x2)(x4)3x22
x^2-2=(x+2)(x-2)x22=(x+2)(x2)
So the function will became:
f(x)=[(x-4)^3]/(x+2)f(x)=(x4)3x+2
Now
f'(x)=d/dx[(x-4)^3]/(x+2)
f'(x)=[3(x+2)(x-4)^2-(x-4)^3]/(x+2)^2
For local extremum point
f'(x)=0
So
[3(x+2)(x-4)^2-(x-4)^3]/(x+2)^2=0
[3(x+2)(x-4)^2-(x-4)^3]=0
3(x+2)(x-4)^2=(x-4)^3
3x+6=x-4
2x=-10
x=-5