- #1

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d²y/ dx² = - h y / j

where h, j are constants. What's y?

where h, j are constants. What's y?

- Thread starter youngoldman
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- #1

- 15

- 0

d²y/ dx² = - h y / j

where h, j are constants. What's y?

where h, j are constants. What's y?

- #2

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- #3

gabbagabbahey

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Can you think of a function whose second derivative is proportional to it?

- #4

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- #5

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- #6

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In other words I know it's in the form

y = Aexp(c) + B exp (-c), just not sure what the c is.

y = Aexp(c) + B exp (-c), just not sure what the c is.

- #7

gabbagabbahey

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- #8

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so it is a complex argument as I was expecting because a complex exp can be written in terms of sines and cosines, whose 2nd derivative is their own negative.

- #9

gabbagabbahey

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Yes, exactly so you may as well write [itex]y(x)=Csin(\frac{h}{j}x)+Dcos(\frac{h}{j}x)[/itex]

- #10

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Thank you, gabbagabbahey.

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