Any help would be massively appreciated
A vehicle of mass m=1000kg is brought to rest by a force F given by $$F=(0.5+4x)10^3 N$$ Where $x $is distance in metres. Given that according time I the Second Newtons law $$F=m\frac{d^2x}{dt^2}$$ find an expression for $x$ in terms of $t$.
Solve the differential equation
$$x''(t)-40x(t)=5.$$