Rank theorem
About points...
We associate a certain number of points with each exercise.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.
That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.
That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.
About difficulty...
We associate a certain difficulty with each exercise.
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.
That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:
Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise
Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise
Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise
Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise
Level 5 -
Level 6 -
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.
That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:
Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise
Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise
Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise
Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise
Level 5 -
Level 6 -
Question
Solution
Short
Video
\(\LaTeX\)
No explanation / solution video to this exercise has yet been created.
Visit our YouTube-Channel to see solutions to other exercises.
Don't forget to subscribe to our channel, like the videos and leave comments!
Visit our YouTube-Channel to see solutions to other exercises.
Don't forget to subscribe to our channel, like the videos and leave comments!
Exercise:
Let T:Vlongrightarrow W be a linear map where V is finite dimensional. Then textdim KerT+textdim ImTtextdimV.
Solution:
Proof. Write n:textdimV. Let u_...u_k be a basis for textKerT. Since textKerT is a subspace of V it is also finite dimensional. Ext u_...u_k to a basis u_...u_kv_...v_n-k of V. bf By a previous Lemma: textImTtextSpTu_...Tu_kv_...v_n-ktextSpTv_...Tv_n-k We claim that Tv_...Tv_n-k form a basis for textImT. Indeed we have just proven that Tv_...Tv_n-k span textImT so it remains to show that Tv_...Tv_n-k are linearly indepent. To see this let a_...a_n-kin K and ase _i^n-ka_iTv_i Since T is linear Tleft_i^n-ka_iv_iright_i^n-ka_iTv_i &Longrightarrow _i^n-ka_iv_i in textKerT textNow u_...u_kquad textis a basis of KerT. &Longrightarrow exists b_...b_k in K : a_v_+...+a_n-kv_n-kb_u_+...+b_ku_k &Longrightarrow a_v_+...+a_n-kv_n-k+-b_u_+...+-b_ku_k. But u_...u_kv_...v_n-k are linearly indepent they form a basis of V. Longrightarrow a_...a_n-k b_...b_k. This proves that Tv_...Tv_n-k form a basis for textImT. bf Conclusion: textdim ImTn-ktextdimV-textdim KerT &Longrightarrow textdim KerT+textdim ImTtextdimV
Let T:Vlongrightarrow W be a linear map where V is finite dimensional. Then textdim KerT+textdim ImTtextdimV.
Solution:
Proof. Write n:textdimV. Let u_...u_k be a basis for textKerT. Since textKerT is a subspace of V it is also finite dimensional. Ext u_...u_k to a basis u_...u_kv_...v_n-k of V. bf By a previous Lemma: textImTtextSpTu_...Tu_kv_...v_n-ktextSpTv_...Tv_n-k We claim that Tv_...Tv_n-k form a basis for textImT. Indeed we have just proven that Tv_...Tv_n-k span textImT so it remains to show that Tv_...Tv_n-k are linearly indepent. To see this let a_...a_n-kin K and ase _i^n-ka_iTv_i Since T is linear Tleft_i^n-ka_iv_iright_i^n-ka_iTv_i &Longrightarrow _i^n-ka_iv_i in textKerT textNow u_...u_kquad textis a basis of KerT. &Longrightarrow exists b_...b_k in K : a_v_+...+a_n-kv_n-kb_u_+...+b_ku_k &Longrightarrow a_v_+...+a_n-kv_n-k+-b_u_+...+-b_ku_k. But u_...u_kv_...v_n-k are linearly indepent they form a basis of V. Longrightarrow a_...a_n-k b_...b_k. This proves that Tv_...Tv_n-k form a basis for textImT. bf Conclusion: textdim ImTn-ktextdimV-textdim KerT &Longrightarrow textdim KerT+textdim ImTtextdimV
Meta Information
Exercise:
Let T:Vlongrightarrow W be a linear map where V is finite dimensional. Then textdim KerT+textdim ImTtextdimV.
Solution:
Proof. Write n:textdimV. Let u_...u_k be a basis for textKerT. Since textKerT is a subspace of V it is also finite dimensional. Ext u_...u_k to a basis u_...u_kv_...v_n-k of V. bf By a previous Lemma: textImTtextSpTu_...Tu_kv_...v_n-ktextSpTv_...Tv_n-k We claim that Tv_...Tv_n-k form a basis for textImT. Indeed we have just proven that Tv_...Tv_n-k span textImT so it remains to show that Tv_...Tv_n-k are linearly indepent. To see this let a_...a_n-kin K and ase _i^n-ka_iTv_i Since T is linear Tleft_i^n-ka_iv_iright_i^n-ka_iTv_i &Longrightarrow _i^n-ka_iv_i in textKerT textNow u_...u_kquad textis a basis of KerT. &Longrightarrow exists b_...b_k in K : a_v_+...+a_n-kv_n-kb_u_+...+b_ku_k &Longrightarrow a_v_+...+a_n-kv_n-k+-b_u_+...+-b_ku_k. But u_...u_kv_...v_n-k are linearly indepent they form a basis of V. Longrightarrow a_...a_n-k b_...b_k. This proves that Tv_...Tv_n-k form a basis for textImT. bf Conclusion: textdim ImTn-ktextdimV-textdim KerT &Longrightarrow textdim KerT+textdim ImTtextdimV
Let T:Vlongrightarrow W be a linear map where V is finite dimensional. Then textdim KerT+textdim ImTtextdimV.
Solution:
Proof. Write n:textdimV. Let u_...u_k be a basis for textKerT. Since textKerT is a subspace of V it is also finite dimensional. Ext u_...u_k to a basis u_...u_kv_...v_n-k of V. bf By a previous Lemma: textImTtextSpTu_...Tu_kv_...v_n-ktextSpTv_...Tv_n-k We claim that Tv_...Tv_n-k form a basis for textImT. Indeed we have just proven that Tv_...Tv_n-k span textImT so it remains to show that Tv_...Tv_n-k are linearly indepent. To see this let a_...a_n-kin K and ase _i^n-ka_iTv_i Since T is linear Tleft_i^n-ka_iv_iright_i^n-ka_iTv_i &Longrightarrow _i^n-ka_iv_i in textKerT textNow u_...u_kquad textis a basis of KerT. &Longrightarrow exists b_...b_k in K : a_v_+...+a_n-kv_n-kb_u_+...+b_ku_k &Longrightarrow a_v_+...+a_n-kv_n-k+-b_u_+...+-b_ku_k. But u_...u_kv_...v_n-k are linearly indepent they form a basis of V. Longrightarrow a_...a_n-k b_...b_k. This proves that Tv_...Tv_n-k form a basis for textImT. bf Conclusion: textdim ImTn-ktextdimV-textdim KerT &Longrightarrow textdim KerT+textdim ImTtextdimV
Contained in these collections: