PROBLEM SET FOR MATH 341 (LINEAR ALGEBRA), FALL 2023 Part 1
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PROBLEM SET FOR MATH 341 (LINEAR ALGEBRA), FALL 2023
Part 1 Bonus Redux
Due November 20, 2023 by 11:59pm
For each of the following problems, show all work and fully justify your answer/s.
One check+/check/check- can be earned for each of the numbered sub/questions (2, 3, 4). Up to two check+/check/check-’s can be earned for question 1.
(1) Let T = TA : Rn → Rn be left-multiplication by ann-by-n matrix A. Show that the following statements are all equivalent.
(i) T is injective.
(ii) T is surjective.
(iii) The system A⃗x =0(⃗) has a unique solution ⃗x =0(⃗) .
(iv) The linear system A⃗x =0(⃗) has no free variables.
(v) For any b(⃗) ∈ Rn , the linear system A⃗x =b(⃗) has a unique solution.
(2) Let T = TA : Rn → Rm be left-multiplication by an m-by-n matrix A
(with no assumptions on m and n, other than they are finite). Show that
the following statements are equivalent:
(i) T is injective.
(ii) The system A⃗x =0(⃗) has a unique solution ⃗x =0(⃗) .
(iii) The linear system A⃗x =0(⃗) has no free variables.
(iv) For any b(⃗) ∈ Rn , the linear system A⃗x =b(⃗) has at most one solution. (3) Let T = TA : Rn → Rm be left-multiplication by an m-by-n matrix A
(with no assumptions on m and n, other than they are finite). Show that
the following statements are equivalent:
(i) T is surjective.
(ii) For any b(⃗) ∈ Rn , the linear system A⃗x =b(⃗) has at least one solution. (4) Let TA : Rn → Rm be left multiplication by an m-by-n matrix A.
(a) Describe the kernel of TA using the language of system of linear equa- tions.
(b) Describe a spanning set for the image using the matrix A
2023-10-24