       Three masses and four springs

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• Subject: [mg132597] Three masses and four springs
• From: Robert Jenkins <dale.jenkins8 at gmail.com>
• Date: Wed, 16 Apr 2014 03:40:27 -0400 (EDT)
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```The instruction
DSolve[{-2*x1[t] + x2[t] == x1''[t], -2*x2[t] + x1[t] == x2''[t],
x1 == -1, x2 == 2, x1' == 0, x2' == 0}, {x1, x2}, t]
produces a simple solution. But I am surprised to find the three-mass version produces a mass of complication. Have I made a mistake?
DSolve[{-2*x1[t] + x2[t] == x1''[t], -2*x2[t] + x3[t] + x1[t] ==
x2''[t], -2*x3[t] + x2[t] == x3''[t], x1 == -1, x2 == 2,
x3 == -1, x1' == 0, x2' == 0, x3' == 0}, {x1, x2, x3},
t]

```

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