When factorising quadratics (or any trinomial) first identify the form of the expression and then apply the most direct method. If the expression is not in a recognisable form then manipulate it so that it is.
Multiplying matrices is fairly simple but there is a process to learn and a couple of rules to remember.
Matrix addition and subtraction is fairly simple. Just remember that we can only add or subtract matrices if they have the same dimensions. The number of rows must be equal in each matrix and the number of columns must be equal in each matrix.
Matrices are simply arrays of values. We use them as a tool to ease operations such as solving simultaneous equations, working with vectors and transformations.
It is fairly simple to memorise the formula for the determinant of a 2×2 matrix:
Here we look at a simple approach that aids memorising the formula for a 3×3 matrix called Sarrus’ rule which will give you the determinant of a 3×3 matrix.
Craig Rose
