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