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matrix
a rectangular array of elements (or entries) set out by rows and columns
Column
vertical linear array of numbers
row
a hortizontal array of numbers side by side
zero matrix
matrix containing zeros
diagonal matrix
has zeros in all positions other than the leading diagonal which contains numbers other than zero.
elements
What are the objects in a set called?
matrices
plural of matrix
(m X n) matrix
A matrix with m rows and n columns
3B
B + B + B
Subtraction of matrix
subtracting corresponding elements
only on matrices of the same order
multiplication by a scalar (number)
each element is multiplied by the scalar
equality of matrices
matrices are equal if they are of the same order and all corresponding elements are equal
identity matrix
diagonal matrix with ones in the leading diagonal and zeros in the other positions.
square matrix
the same number of elements in the rows and columns.
A X B exists and order is m X p
A = m X n and B = n X p, then A X B
AI = IA
A is a square matrix and I is the identity matrix
A^-1
inverse matrix
AX = B
X = A^-1X B
XA = B
X = BA^-1
entries
the numbers in a matrix
dimensions, example
2 by 3
rows
what does the 2 represent in 2x3
columns
what does the 3 represent in 2x3
row matrix
a matrix has only 1 row
column matrix
a matrix has only 1 column
how are two matrices equal?
if their dimensions are the same and the entries in corresponding positions are equal
the dimensions have to be the same
what must occur in order for matrices to be able to be added and subtracted?
what is the communitive property?
axb is the same as bxa
No
are matrices communitive?
what is the associative property?
a(bc) is the same as (ab)c
Yes
are matrices associative?
det A or |A|
how is a determinant denoted by?
keep the area positive
when finding the area of the triangle, what do you always do?
5+0=5 or 5x1=5
what is the identity property?
5+ (-5)= 0
what is the inverse property?
multiply by 1 0
in a 2x2 matrix, how do you get the multiplicative identity?
multiply by 1 0 0
in a 3x3 matrix, how do you get the multiplicative identity?
equal matrices
-dimensions are the same
matrix multiplication
-can be multiplied if the # of A columns = # of B rows
does not hold true
commutative property of matrix multiplication
The additive identity is 0. a + 0 = 0 + a = a
the opposite of a number
Multiplicative Identity
A * 1 = A
multiplicative inverse
reciprocal of a number
determinants
2x2 (cross multiply and subtract)
multiply the matrix by a matrix with all zeros
multiply the matrix by a matrix by the same matrix except all entries are negated
multiplicative identity matrices
only for square matrices- (nxn) with a diagonal of 1s from left to right
multiplicative inverse matrices
1/det [d -b -c a]
solving matrix equa
[A] X = [B] (multiply A(-1) times B = X)
solving systems with matrices
8x + 5y = 2
Transformation
a movement on the cartesian plane
[1 0, 0 -1]