find a recursive relation for the characteristic polynomial of the $k times k $ matrix?
find a recursive relation for the characteristic polynomial of the $k times k $ matrix $$begin{pmatrix} 0 & 1 \ 1 & 0 & 1 \ mbox{ } & 1 & . & . \ mbox{ } &mbox{ } & . & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & 0end{pmatrix}$$
and compute the polynomial for $kle 5$
My attempt : Let $M_k$ be the $ktimes k$ matrix and $P_k(x)=det(M_k-xI_k)$ be its characteristic polynomial. We have
$$P_k(x)=detbegin{pmatrix} -x & 1 \ 1 & -x & 1 \ mbox{ } & 1 & ddots & ddots \ mbox{ } &mbox{ } & ddots & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & -xend{pmatrix}$$
after that im not able proceed further
Any hints/solution will be appreciated
linear-algebra
|
show 4 more comments
find a recursive relation for the characteristic polynomial of the $k times k $ matrix $$begin{pmatrix} 0 & 1 \ 1 & 0 & 1 \ mbox{ } & 1 & . & . \ mbox{ } &mbox{ } & . & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & 0end{pmatrix}$$
and compute the polynomial for $kle 5$
My attempt : Let $M_k$ be the $ktimes k$ matrix and $P_k(x)=det(M_k-xI_k)$ be its characteristic polynomial. We have
$$P_k(x)=detbegin{pmatrix} -x & 1 \ 1 & -x & 1 \ mbox{ } & 1 & ddots & ddots \ mbox{ } &mbox{ } & ddots & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & -xend{pmatrix}$$
after that im not able proceed further
Any hints/solution will be appreciated
linear-algebra
2
do it first for $k=2$ and $k=3. ;$ I found a quote "There is nothing impossible to him who will try."
– Will Jagy
Jan 4 at 22:15
ya ,,,im trying @WillJagy.....haa
– jasmine
Jan 4 at 22:17
what do you get for $k=2?$
– Will Jagy
Jan 4 at 22:19
2
now do $k=3.$ By the way, there is a pretty good recipe for writing the char poly in dimension 3, where $sigma_1$ is the trace and $sigma_3$ is the determinant, we also need $sigma_2$ which is the sum of the little 2 by 2 prinipal minor determintns, Then char poly is $x^3 - sigma_1 x^2 + sigma_2 x - sigma_3.$ I think there is also a recipe for $sigma_2$ involving traces of the matrix squared, I will see if I can find that. Worth getting right and memorizing for dimension 2 and 3
– Will Jagy
Jan 4 at 22:24
1
Alright, worked it out, for matrix $M,$ $$sigma_2 = frac{1}{2} left( sigma_1^2 - operatorname{trace} M^2 right)$$ where $sigma_1 = operatorname{trace} M$ as i indicated
– Will Jagy
Jan 4 at 22:35
|
show 4 more comments
find a recursive relation for the characteristic polynomial of the $k times k $ matrix $$begin{pmatrix} 0 & 1 \ 1 & 0 & 1 \ mbox{ } & 1 & . & . \ mbox{ } &mbox{ } & . & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & 0end{pmatrix}$$
and compute the polynomial for $kle 5$
My attempt : Let $M_k$ be the $ktimes k$ matrix and $P_k(x)=det(M_k-xI_k)$ be its characteristic polynomial. We have
$$P_k(x)=detbegin{pmatrix} -x & 1 \ 1 & -x & 1 \ mbox{ } & 1 & ddots & ddots \ mbox{ } &mbox{ } & ddots & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & -xend{pmatrix}$$
after that im not able proceed further
Any hints/solution will be appreciated
linear-algebra
find a recursive relation for the characteristic polynomial of the $k times k $ matrix $$begin{pmatrix} 0 & 1 \ 1 & 0 & 1 \ mbox{ } & 1 & . & . \ mbox{ } &mbox{ } & . & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & 0end{pmatrix}$$
and compute the polynomial for $kle 5$
My attempt : Let $M_k$ be the $ktimes k$ matrix and $P_k(x)=det(M_k-xI_k)$ be its characteristic polynomial. We have
$$P_k(x)=detbegin{pmatrix} -x & 1 \ 1 & -x & 1 \ mbox{ } & 1 & ddots & ddots \ mbox{ } &mbox{ } & ddots & . &. & mbox{ } \ mbox{ } &mbox{ } &mbox{ } & . & . & 1 \ mbox{ } & mbox{ } & mbox{ } & mbox{ } & 1 & -xend{pmatrix}$$
after that im not able proceed further
Any hints/solution will be appreciated
linear-algebra
linear-algebra
asked Jan 4 at 22:13
jasminejasmine
1,640416
1,640416
2
do it first for $k=2$ and $k=3. ;$ I found a quote "There is nothing impossible to him who will try."
– Will Jagy
Jan 4 at 22:15
ya ,,,im trying @WillJagy.....haa
– jasmine
Jan 4 at 22:17
what do you get for $k=2?$
– Will Jagy
Jan 4 at 22:19
2
now do $k=3.$ By the way, there is a pretty good recipe for writing the char poly in dimension 3, where $sigma_1$ is the trace and $sigma_3$ is the determinant, we also need $sigma_2$ which is the sum of the little 2 by 2 prinipal minor determintns, Then char poly is $x^3 - sigma_1 x^2 + sigma_2 x - sigma_3.$ I think there is also a recipe for $sigma_2$ involving traces of the matrix squared, I will see if I can find that. Worth getting right and memorizing for dimension 2 and 3
– Will Jagy
Jan 4 at 22:24
1
Alright, worked it out, for matrix $M,$ $$sigma_2 = frac{1}{2} left( sigma_1^2 - operatorname{trace} M^2 right)$$ where $sigma_1 = operatorname{trace} M$ as i indicated
– Will Jagy
Jan 4 at 22:35
|
show 4 more comments
2
do it first for $k=2$ and $k=3. ;$ I found a quote "There is nothing impossible to him who will try."
– Will Jagy
Jan 4 at 22:15
ya ,,,im trying @WillJagy.....haa
– jasmine
Jan 4 at 22:17
what do you get for $k=2?$
– Will Jagy
Jan 4 at 22:19
2
now do $k=3.$ By the way, there is a pretty good recipe for writing the char poly in dimension 3, where $sigma_1$ is the trace and $sigma_3$ is the determinant, we also need $sigma_2$ which is the sum of the little 2 by 2 prinipal minor determintns, Then char poly is $x^3 - sigma_1 x^2 + sigma_2 x - sigma_3.$ I think there is also a recipe for $sigma_2$ involving traces of the matrix squared, I will see if I can find that. Worth getting right and memorizing for dimension 2 and 3
– Will Jagy
Jan 4 at 22:24
1
Alright, worked it out, for matrix $M,$ $$sigma_2 = frac{1}{2} left( sigma_1^2 - operatorname{trace} M^2 right)$$ where $sigma_1 = operatorname{trace} M$ as i indicated
– Will Jagy
Jan 4 at 22:35
2
2
do it first for $k=2$ and $k=3. ;$ I found a quote "There is nothing impossible to him who will try."
– Will Jagy
Jan 4 at 22:15
do it first for $k=2$ and $k=3. ;$ I found a quote "There is nothing impossible to him who will try."
– Will Jagy
Jan 4 at 22:15
ya ,,,im trying @WillJagy.....haa
– jasmine
Jan 4 at 22:17
ya ,,,im trying @WillJagy.....haa
– jasmine
Jan 4 at 22:17
what do you get for $k=2?$
– Will Jagy
Jan 4 at 22:19
what do you get for $k=2?$
– Will Jagy
Jan 4 at 22:19
2
2
now do $k=3.$ By the way, there is a pretty good recipe for writing the char poly in dimension 3, where $sigma_1$ is the trace and $sigma_3$ is the determinant, we also need $sigma_2$ which is the sum of the little 2 by 2 prinipal minor determintns, Then char poly is $x^3 - sigma_1 x^2 + sigma_2 x - sigma_3.$ I think there is also a recipe for $sigma_2$ involving traces of the matrix squared, I will see if I can find that. Worth getting right and memorizing for dimension 2 and 3
– Will Jagy
Jan 4 at 22:24
now do $k=3.$ By the way, there is a pretty good recipe for writing the char poly in dimension 3, where $sigma_1$ is the trace and $sigma_3$ is the determinant, we also need $sigma_2$ which is the sum of the little 2 by 2 prinipal minor determintns, Then char poly is $x^3 - sigma_1 x^2 + sigma_2 x - sigma_3.$ I think there is also a recipe for $sigma_2$ involving traces of the matrix squared, I will see if I can find that. Worth getting right and memorizing for dimension 2 and 3
– Will Jagy
Jan 4 at 22:24
1
1
Alright, worked it out, for matrix $M,$ $$sigma_2 = frac{1}{2} left( sigma_1^2 - operatorname{trace} M^2 right)$$ where $sigma_1 = operatorname{trace} M$ as i indicated
– Will Jagy
Jan 4 at 22:35
Alright, worked it out, for matrix $M,$ $$sigma_2 = frac{1}{2} left( sigma_1^2 - operatorname{trace} M^2 right)$$ where $sigma_1 = operatorname{trace} M$ as i indicated
– Will Jagy
Jan 4 at 22:35
|
show 4 more comments
1 Answer
1
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oldest
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Hint: Look at the formula for the determinant of using the first row.
Then you get a recursive definition for the determinant.
Solution:
$P_k(x)=-xP_{k-1}(x)-P_{k-1}(-1)$
New contributor
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Hint: Look at the formula for the determinant of using the first row.
Then you get a recursive definition for the determinant.
Solution:
$P_k(x)=-xP_{k-1}(x)-P_{k-1}(-1)$
New contributor
add a comment |
Hint: Look at the formula for the determinant of using the first row.
Then you get a recursive definition for the determinant.
Solution:
$P_k(x)=-xP_{k-1}(x)-P_{k-1}(-1)$
New contributor
add a comment |
Hint: Look at the formula for the determinant of using the first row.
Then you get a recursive definition for the determinant.
Solution:
$P_k(x)=-xP_{k-1}(x)-P_{k-1}(-1)$
New contributor
Hint: Look at the formula for the determinant of using the first row.
Then you get a recursive definition for the determinant.
Solution:
$P_k(x)=-xP_{k-1}(x)-P_{k-1}(-1)$
New contributor
edited Jan 4 at 23:05
J.G.
23.5k22237
23.5k22237
New contributor
answered Jan 4 at 22:34
A. PA. P
1085
1085
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2
do it first for $k=2$ and $k=3. ;$ I found a quote "There is nothing impossible to him who will try."
– Will Jagy
Jan 4 at 22:15
ya ,,,im trying @WillJagy.....haa
– jasmine
Jan 4 at 22:17
what do you get for $k=2?$
– Will Jagy
Jan 4 at 22:19
2
now do $k=3.$ By the way, there is a pretty good recipe for writing the char poly in dimension 3, where $sigma_1$ is the trace and $sigma_3$ is the determinant, we also need $sigma_2$ which is the sum of the little 2 by 2 prinipal minor determintns, Then char poly is $x^3 - sigma_1 x^2 + sigma_2 x - sigma_3.$ I think there is also a recipe for $sigma_2$ involving traces of the matrix squared, I will see if I can find that. Worth getting right and memorizing for dimension 2 and 3
– Will Jagy
Jan 4 at 22:24
1
Alright, worked it out, for matrix $M,$ $$sigma_2 = frac{1}{2} left( sigma_1^2 - operatorname{trace} M^2 right)$$ where $sigma_1 = operatorname{trace} M$ as i indicated
– Will Jagy
Jan 4 at 22:35