A system of equations is a set of equations of more than 1 variable. In a system
of equations, we want to find the values of the variable which will satisfy each of the
equations. We typically divide these types of systems into two types, linear and
nonlinear

Linear Systems

Linear Systems are systems in which all equations
can be expressed in terms of addition and subtraction of multiples of a fwe unknown variables.

The following are examples of linear systems

example 1

3 x + 2 y = 4

2 x - 6 y = 5

exmaple 2

3 x = 4 (trivial...but linear)

exmaple 3

3 x + 2 y = 4

2 x - 6 y + 5 z = 5

2 x - 6 y - z = 5

Nonlinear Systems

Nonlinear systems of equations are characterized by having terms
which cannot be formed by simply adding together multiples of the
unknown variables. Possibly unknowns are exponetiated, multiplied
together, or are the arguments of a function.