Solution
= Solution
Differentiate $v'=u$ once, then substitute the other equation. The required <second-order linear differential equation> is
$$
\boxed{v''=u'=4v+2,\qquad v''-4v=2.}
$$
= Solution
Differentiate $v'=u$ once, then substitute the other equation. The required <second-order linear differential equation> is
$$
\boxed{v''=u'=4v+2,\qquad v''-4v=2.}
$$