Here x1,x2, . . . ,xn are the unknowns, a11,a12, . . . ,amn are the coefficients of the system, and b1,b2, . . . ,bm are the constant terms. The coefficients and unknowns can be integers, real or complex numbers. One very popular and useful approach is to take each unknown as a weight for a column vector in a linear combination as shown below.