Math Is Fun Forum

Zeeshan 01

Member

Registered: 2016-07-22

Posts: 746

Last step

Finding point of inflection
Fx= 2/x-4/x^2
I take second derivative tesr that is
4(x-6)/x^4
And point of inflection is 6 but in book there is two point of inflection 2/9 ,6

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Malik

Bob

Administrator

Registered: 2010-06-20

Posts: 10,619

Re: Last step

x = 6, y = 2/9 is a point of inflexion.  Cannot find any others.

Bob

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Grantingriver

Member

Registered: 2016-02-01

Posts: 129

Re: Last step

Your answer is correct, but you have made a mistake and misunderstood the book. The point of inflection is not x in fact any point is an ordered pain (x,y) so the value of x which you have found is the first component of the point of inflection and the second component (which is y) can be found by substituting x=6 in the original equation, so we have:

hence the point of inflection is (6,2/9) which is the answer found in your book. I hope that will help.