Convert the second order equation

$\displaystyle \frac{d^2y}{dt^2}=0$

into a first order system using:

$\displaystyle v=\frac{dy}{dt}$

Then find the general solution for $\displaystyle \frac{dv}{dt}$ equation then sub the solution into the $\displaystyle \frac{dy}{dt}$ equation and find the solution of the system.

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I'm not really sure with this but

$\displaystyle \frac{dy}{dt}=v , \frac{dv}{dt}=0$

so $\displaystyle y(t)=k_1*e^t, v(t)=k_2$

Then I have no idea. Some help would be very appreciated.