General statements for the second derivative of a function
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I am working on a task about second derivative. The task is:
$f(x)$ on $(-1,1)$ has the values $f(-1)=-10$, $f(0)=-10$ and $f(1)=-3$.
What can you say about the values for first and second derivative?
For the first derivative I use the mean value theorem and find $f'(c)$ for different intervals.
For the second derivative I have some statements:
1) $|f '' (c)|>frac72$
2) $|f '' (c)|>7$
Are there any theorems or rules I can use in order to check if these statements are true or not?
Thanks!
calculus functions
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up vote
1
down vote
favorite
I am working on a task about second derivative. The task is:
$f(x)$ on $(-1,1)$ has the values $f(-1)=-10$, $f(0)=-10$ and $f(1)=-3$.
What can you say about the values for first and second derivative?
For the first derivative I use the mean value theorem and find $f'(c)$ for different intervals.
For the second derivative I have some statements:
1) $|f '' (c)|>frac72$
2) $|f '' (c)|>7$
Are there any theorems or rules I can use in order to check if these statements are true or not?
Thanks!
calculus functions
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I am working on a task about second derivative. The task is:
$f(x)$ on $(-1,1)$ has the values $f(-1)=-10$, $f(0)=-10$ and $f(1)=-3$.
What can you say about the values for first and second derivative?
For the first derivative I use the mean value theorem and find $f'(c)$ for different intervals.
For the second derivative I have some statements:
1) $|f '' (c)|>frac72$
2) $|f '' (c)|>7$
Are there any theorems or rules I can use in order to check if these statements are true or not?
Thanks!
calculus functions
I am working on a task about second derivative. The task is:
$f(x)$ on $(-1,1)$ has the values $f(-1)=-10$, $f(0)=-10$ and $f(1)=-3$.
What can you say about the values for first and second derivative?
For the first derivative I use the mean value theorem and find $f'(c)$ for different intervals.
For the second derivative I have some statements:
1) $|f '' (c)|>frac72$
2) $|f '' (c)|>7$
Are there any theorems or rules I can use in order to check if these statements are true or not?
Thanks!
calculus functions
calculus functions
edited Sep 9 at 13:51
rogerl
16.7k22745
16.7k22745
asked Sep 9 at 13:40
netwon1227
119110
119110
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add a comment |Â
1 Answer
1
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0
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Hint
If we consider $xin(-1,1)$ then
$$|f'(x)|le kimplies |f(x)-f(0)|le kleft|xright|le kimplies |f(1)-f(0)|le k.$$
Since $f(1)-f(0)=7,$ what can we say about $k?$
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
Hint
If we consider $xin(-1,1)$ then
$$|f'(x)|le kimplies |f(x)-f(0)|le kleft|xright|le kimplies |f(1)-f(0)|le k.$$
Since $f(1)-f(0)=7,$ what can we say about $k?$
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
add a comment |Â
up vote
0
down vote
Hint
If we consider $xin(-1,1)$ then
$$|f'(x)|le kimplies |f(x)-f(0)|le kleft|xright|le kimplies |f(1)-f(0)|le k.$$
Since $f(1)-f(0)=7,$ what can we say about $k?$
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Hint
If we consider $xin(-1,1)$ then
$$|f'(x)|le kimplies |f(x)-f(0)|le kleft|xright|le kimplies |f(1)-f(0)|le k.$$
Since $f(1)-f(0)=7,$ what can we say about $k?$
Hint
If we consider $xin(-1,1)$ then
$$|f'(x)|le kimplies |f(x)-f(0)|le kleft|xright|le kimplies |f(1)-f(0)|le k.$$
Since $f(1)-f(0)=7,$ what can we say about $k?$
edited Sep 9 at 14:02
answered Sep 9 at 13:56
mfl
25.2k12141
25.2k12141
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
add a comment |Â
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
We can say that k>= 7 , but I don't see how it can say anything about f ''(x). Sorry.
â netwon1227
Sep 9 at 14:40
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
There exist $a,bin (-1,1)$ such that $f'(a)=0$ and $f'(b)>7.$ Use that $7<f'(b)-f'(a)=f''(c)(b-a).$ What do you get?
â mfl
Sep 9 at 15:05
add a comment |Â
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