Question

How do you find the inflection points of `f(x)=x^5-30x^3`?

Answer 1

0 and -3

Explanation:

`df(x)=5x^4-90x^2`
`d(df(x))=20x^3-180x`
`20x^3-180x=0`
`x=0; x=3; x=-3`
`g(x)=d(d(df(x)))=60x^2-180`
`g(0)=-180; g(3)=0; g(-3)=1080`
3 is not infection point.