Matrices

A matrix is an arrangement of elements (usually numbers and letters) in rows and columns.

The order or size of a matrix is the number of rows by the number of columns. e.g. 2 x 3 matrices has 2 rows and 3 columns.

Matrices can be added or subtracted only if they are of the same order.

To multiply matrices no. of columns in 1st matrix = no. of rows in 2nd matrix.

A matrix X is SINGULAR if the determinant is o, i.e  $\left|X\right|\ or\ Det.\ X\ =0$  

Inverse matrix, A $A^{-1}=\frac{1}{\left|A\right|}\times A\ adjoint$  

To solve simultaneous equations, use the form  $X=A^{-1}B$