§1.2 Gaussian and Gauss-Jordan Elimination1.Definition:A matrix is a rectangular array of numbers.Thenumbers in the array are called the entries in the matrix.A generalm×nmatrix can be written asA=a11a12· · ·a1na21a22· · ·a2n.........am1am2· · ·amnWe can also simply denote this matrix asA= [aij]m×n= [aij]Ifm=n, the matrix is called a square matrix of orderm,anda11, a22,· · ·, annare called the main diagonal entries ofA.-50701-20,-50-20,h-50-204i-5802-26,23-510-8-2052,h-5i1
2. Elementary Row Operations for Matrices:1. (Replacement) Replace one row by the sum of itself and a multipleof another row.2. (Interchange) Interchange two rows.3. (Scaling) Multiply all entries in a row by a nonzero constant.