<exercise masterit-seed="5044" masterit-slug="C3" masterit-name="Homogeneous second-order linear ODE">
<statement>
<p>Explain how to find the general solution to each given ODE using
exponential functions.</p>
<p>For each exponential solution using complex numbers, also provide
an alternate general solution using only real numbers.</p>
<ol>
<li>
<me> 39 \, {x} + 3 \, {x''} = 18 \, {x'} </me>
</li>
<li>
<me> -128 \, {y} = 32 \, {y'} + 2 \, {y''} </me>
</li>
</ol>
</statement>
<answer>
<me> {x} = c_{1} e^{\left(\left(2 i + 3\right) \, t\right)} + c_{2} e^{\left(-\left(2 i - 3\right) \, t\right)} </me>
<me> {x} = {\left(d_{1} \cos\left(2 \, t\right) + d_{2} \sin\left(2 \, t\right)\right)} e^{\left(3 \, t\right)} </me>
<me> {y} = k_{1} t e^{\left(-8 \, t\right)} + k_{2} e^{\left(-8 \, t\right)} </me>
</answer>
</exercise>