Matrices Flashcards
1
Q
A matrix has dimensions 2 x 3.
What does this mean?
A
It has 2 rows and 3 columns
2
Q
When can you add and subtract matrices?
A
When they have the same dimensions
3
Q
What is ((A^-1)(B^-1))^-1
A
BA
4
Q
When can you multiply two matrices : A x B
A
When the columns of A = the rows of B
5
Q
What are the dimensions of C:
A x B = C
A
Dimensions: the rows of A x the columns of B
6
Q
Give the 3x3 matrix corresponding to a reflection in the y=0 plane
A
1 0 0
0 -1 0
0 0 1
7
Q
Give the 3x3 matrix corresponding to a reflection in the x=0 plane
A
-1 0 0
0 1 0
0 0 1
8
Q
Give the 3x3 matrix corresponding to a reflection in the xy plane
A
xy plane <=> z=0 plane
1 0 0
0 1 0
0 0 1
9
Q
What is the inverse of the 2x2 matrix:
a b
c d
A
d -b
-c b
then divide by the determinant (formatting this is hard)
