System of linear equations
In mathematics, a system of linear equations (or linear system) is a collection of two or more linear equations involving the same variables. For example, { 3 x + 2 y − z = 1 2 x − 2 y + 4 z = − 2 − x + 1 2 y − z = 0 {\displaystyle {\begin{cases}3x+2y-z=1\\2x-2y+4z=-2\\-x+{\frac {1}{2}}y-z=0\end{cases}}} is a system of three equations in the three variables x, y, z.
Source: Wikipedia — System of linear equations (CC BY-SA 4.0)