Electrical and mechanical engineers, chemists, biologists and scientists all need knowledge of matrices to solve problems. In computer graphics, matrices are used to project a 3-dimensional image on to a 2-dimentional screen, and to create realistic motion. Matrices are therefore very important in solving engineering problems. Matrices and determinants are mainly used for the solution of linear simultaneous equations. Matrices cannot be expressed as a single numerical value, but they can often be simplified or combined, and unknown element values can be determined by comparison methods. Just as there are rules for addition, subtraction, multiplication and division of numbers in arithmetic, rules for these operations can be applied to matrices and the rules of matrices are such that they obey most of those governing the algebra of numbers.