Precalculus by Richard Wright
Systems of equations can be used to find solutions to problems that have multiple variables and equations. An application of systems of inequalities is linear programming which is a method to maximize or minimize a function based on constraints. In business and economics, linear programming can be used to maximize profits or minimize costs. Another use is a method to stabilize camera motions in videos by minimizing the acceleration and jerk of the camera paths.
8-01 Nonlinear and Linear Systems
8-02 Two-Variable Linear Systems