MAT224H1 Linear Algebra II - Summer 2022 Midterm Test
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MAT224H1 Linear Algebra II - Summer 2022
Midterm Test
1. Decide if the following statement is True or False:
Let R+ = {r ∈ R|r > 0}, and V = (R+ )n = {(x1 , . . . , xn ) | xi ∈ R+ for each i}.
Define a vector sum operation +′ and a scalar multiplication operation .′ by:
(x1 , . . . , xn ) +′ (y1 , . . . , yn ) = (x1 y1 , . . . , xn yn ),
c .′ (x1 , . . . , xn ) = (x1(c) , . . . , xn(c)).
Then V is a vector space with these two operations.
Indicate your final answer by filling in exactly one circle below (unfilled ◦ filled •) and justify your choice with a proof or counter-example. [5 marks]
© True
© False
2. Decide if the following statement is True or False:
Let U and V be finite dimensional vector spaces, and let T ∈ L(U, V). If dim Im T = min{dimU, dimV }, then T is either injective or surjective.
Note: min{A,B} = the minimum of the two values of A and B .
Indicate your final answer by filling in exactly one circle below (unfilled ◦ filled •) and justify your choice with a proof or counter-example. [5 marks]
© True
© False
3. Decide if the following statement is True or False:
Let V be a vector space, and let T : V → R be a linear transformation. Suppose that x, y ∈ V are linearly independent vectors, and that Tx = 3 and Ty = . Then there exists a non-zero vector z ∈ V such that Tz = 0.
Indicate your final answer by filling in exactly one circle below (unfilled ◦ filled •) and justify your choice with a proof or counter-example. [5 marks]
© True
© False
4. Decide if the following statement is True or False:
Suppose U and W are both five-dimensional subspaces of R9 . Then U ∩ W = {0}.
Indicate your final answer by filling in exactly one circle below (unfilled ◦ filled •) and justify your choice with a proof or counter-example. [5 marks]
© True
© False
5. Decide if the following statement is True or False:
Let U, V, W be vector spaces and S : U → V, T : V → W be linear transformations. Then TS is bijective if and only if both S and T are bijective.
Note: T is bijective means T is both injective and surjective.
Indicate your final answer by filling in exactly one circle below (unfilled ◦ filled •) and justify your choice with a proof or counter-example. [5 marks]
© True
© False
6. Suppose V1 , . . . , Vm are vector spaces . Prove that L(V1 × · · · × Vm , W) and L(V1 , W) × · · · × L(Vm , W) are isomorphic vector spaces . [5 marks]
7. Let M and N be n × n matrices . Prove that if M and N are similar, then there is a linear transformation T : Rn → Rn and bases µ and ν for Rn such that [T]µ(µ) = M and [T]ν(ν) = N.
[5 marks]
8. Let V and W be vector spaces with bases α = {v1 , . . . , vn } and β = {w1 , . . . , wm }, respectively. Define a
mapping Mat : L(V, W) → Mm ×n (R) by
Mat (S) = [S]α(β)
for each S ∈ L(V , W).
Show that Mat is a linear mapping from the vector space L(V , W) to the vector space Mm ×n (R). [5 marks]
2022-07-13