Friends I have one doubt
Below given equation is linear or non linear
It's non-linear, because of the cos x coefficient. Compare it to the ODE for a pendulum, which is non-linear, but can be linearized if small deflections are assumed.
Mathematically,the equation you wrote is considered a linear ordinary differential equation with non-constant coefficients. It is considered linear if the homogeneous part is linear with respect to the dependent variable (in this case y).
But what about -5 term
That's not included in the homogeneous part.
Linear, because all exponents of y aren't different of +1.
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