Describe two real life quantities that vary directly with each other and two quantities that vary inversely with each other.

7.1 – Matrix size = number of rows by number of columns Add/Subtract matrices = same size matrices Vector = one column or one row Equality = same size and values 7.2 Multiply matrices – column of first matrix = row of second matrix Ex: (3 X 3 ) ( 3 X 2) = ( 3 X 2) Ex: Multiply matrix and vector Matrix Multiplication = Not Commutative AB BA Transpositions of matrices and vectors A = A = Symmetric matrices square matrices = A = AT Skew Symmetric matrices – A = A Upper Triangle = square matrices = nonzero on and above main diagonal – 0 below main diagonal Lower Triangle = square matrices = nonzero on and below main diagonal – 0 above main diagonal Main Diagonal = 0 or not