Mathematics & Science Learning Center
Computer Laboratory

Applications of Differential Equations

A Suspended Wire

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Your Mathematica session should have gone something like this:

ansol=DSolve[{y''[x]==(0.5/40)*Sqrt[1+(y'[x])^2], y[0]==0, y'[0]==0}, y[x], x]

Mathematica produces a solution wrapped in braces in the form of a replacement rule for y[x]. We want to extract just the right-hand side of this replacement rule, and to shed the braces. This may be done by using what may be called, the "[[1,1,2]] trick."

Use it now, by issuing the command:

ansol1 = ansol[[1, 1, 2]]

Let's go and see what you should have gotten...

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