Question

So I have this problem to solve:http://screencast.com/t/yAgmcoQP

There is no inflection point but...
http://screencast.com/t/ShRELGKpQG

I don't know what that is or how can I find it for myself?

Answer 1

check for f'(x) and f"(x)
any attempt ?

Answer 2

There's no inflection point, i'm about to post this in your other question.

Answer 3

If the answer key shows it has one, then the answer key is wrong. A parabola can't have an inflection point - the concavity never changes (it's always either concave up, or concave down).

Answer 4

so this answer is wrong? http://screencast.com/t/ShRELGKpQG

Answer 5

-4-2x=0
-2x=4
x=-2
even if F is the anti-derivative of f,
the critical point of F would be x=-2

Answer 6

**inflection point

Answer 7

Yep. It was probably meant to be a cubic or quartic or something.

f'' of a parabola is always a positive or negative number...

\[\Large f(x) = ax^2+bx+c\]
\[\Large f'(x) = 2ax+b\]
\[\Large f''(x) = 2a\]
Which is a constant.

Answer 8

in the problem it says "And find the x-coordinates of ALL inflection points"

Answer 9

Maybe thats a hint of some sort?

Answer 10

well, as our agent said, there is no inflection point for f

Answer 11

Don't stress about it Christos, the problem or the answer key is wrong :) There's no inflection points.

Answer 12

I see:( thank you a;; for the help

Answer 13

all*

Answer 14

you find inflection point by equating 2nd derivative to 0....was this discussed?

Answer 15

yea yea

Answer 16

ok, just confirming...

Answer 17

lol don't make a sad face @Christos! Don't worry about it. Either the answer key was for a different question, or the question has the wrong functions written in, or some combination of a cluster-f--- of mistakes.

It's reading too much into it to think that maybe they were really asking for the antiderivative F or something... that's just trying to interpret info in the question that isn't there. It clearly states f. As is, the problem is just broken :)

Answer 18

yeah :D

Answer 19

That's better :D