$2\mathrm{.}11.$ For the shown in P$2\mathrm{.}11,$ the

are undeflected when x$1=$ x$2=$ x$3=0.$ The variable x$2$ rei:ire~;ents

with respect to $.$ Write the mathematical model to describe the motion of the masses as

a set of differential Include nm~f~$.$~f$$nfo VlCPP$-$CIOfl'$7$ ~$-$~fo$.$~U