Math 218 Exam 2 with Questions and Answers
Matrix Multiplication ANSWER only makes sense if # of cols of first matrix = # rows of second matrix
--> if performing A*B: resulting matrix should have
rows = # rows of A
cols = # cols of B
in other words AB ∈ R^mofA x nofB
Column Perspe...
Math 218 Exam 2 with Questions and
Answers
Matrix Multiplication ANSWER only makes sense if # of cols of first matrix = # rows of
second matrix
--> if performing A*B: resulting matrix should have
rows = # rows of A
cols = # cols of B
in other words AB ∈ R^mofA x nofB
Column Perspective ANSWER When multiplying two matrices, the cols of the resulting
matrix are calculated from multiplying the first matrix with each individual col of b (linear
combination) and the resulting vector will go in the corresponding column of the new matrix
Row Perspective ANSWER the (i,j) entry of a matrix product is given by the inner product
<ith row of A, jth col of B>
reduced row echelon form ANSWER matrix R is in reduced row echelon form if
1) any zero-rows are at the bottom
2) first non-zero entry of the other non-zero rows is 1
3) every pivot occurs to the right of the pivots above it
4) all non-pivot entries in a col containing a pivot equal 0
notation : R = rref(R)
rank ANSWER the number of pivot cols in a matrix of row echelon form
ex: rank(R) = 3
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