1. Let A = [ -3 -2 0; 0 2 -6; 6 3 3 ], and let u = [ 1; 14; -9 ] and v = [ -2; 3; 1 ].
(a) Determine if u is in Col A.
(b) Determine if v is in Nul A.
2. Consider the subset of R^2 consisting of vectors of the form [ a; b ], where a, b in R satisfy a + b = 1. Is this a subspace of R^2? Why or why not?
3. Determine if the following vectors form a basis for R^3. Justify your answer.
[ 1; -6; -7 ], [ 3; -4; 7 ], [ -2; 7; 5 ], [ 0; 8; 9 ]
4. A matrix A and an echelon form of A are shown below. Find bases for Col A and Nul A, and find the dimensions of these subspaces.
A = [ 1 -2 9 5 4; 1 -1 6 5 -3; -2 0 -6 1 -2; 4 1 9 1 -9 ] ~ [ 1 -2 9 5 4; 0 1 -3 0 -7; 0 0 0 1 -2; 0 0 0 0 0 ]
5. For each of the following constructions, explain why your answer satisfies the required properties.
(a) If possible, construct a 4 x 5 matrix A with rank(A) = 2.
(b) If possible, construct a 5 x 4 matrix A with rank(A) = 3 and dim Nul(A) = 2.
6. Let b1 = [ 1; -1; 3 ], b2 = [ -1; 4; 1 ], b3 = [ 1; -3; 1 ], x = [ 1; 2; 3 ].
The set B = { b1, b2, b3 } forms a basis for R^3. Find [x]B, the B-coordinate vector of x.