Answer: Hi! A second order differential equation for the function y(t) has the next shape:
[tex]y''(t) + p(t)y'(t) + q(t)y(t) = g(t)[/tex]
Where p(t), q(t) and g(t) are functions of t.
Then a second order differential equation for y is a differential equation involving the second derivative of y.
Is useful to remember that the order in a differential equation tells us the number of derivations involved in our function, for example, a "third order differential equation" is that involving the third derivative of y, but usually for orders above of two, are called "higher orders differential equations"
