Non linear system does not support the property of superposition principle. Output of nonlinear system is never directly proportional to input. We cannot write non linear system in form of independent components but we can convert nonlinear system into linear system. We can find solution of nonlinear systems.
Let us understand it with help of an example:
Assume we have an equation as x2 + x - 3 = 0. We can write it in form of function as well.
Say f(x) = a where f(x) = x2 + x and a = 3,
From above it is clear that it is a non linear system as it is not supporting two basic properties of linear system, which are:
Additivity: Which states that function f(x + y) is equals to f(x) + f(y).
Homogeneity: Which states that function f(ρx) then it is equals to function ρ f(x).
Above equation does not follow two properties of linear system so it is a nonlinear system. We can solve above nonlinear equation by Quadratic Formula.
If it is difficult to get exact output of nonlinear equation then we use graph to examine roots of nonlinear system. For this we use the property f(x) – a = 0.