Mathematics
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OpenStudy (anonymous):
Solve the IVP:
dy/dt=te^(t-y)
y(0)=5
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OpenStudy (jamesj):
Looks separable to me.
OpenStudy (anonymous):
How so?
OpenStudy (jamesj):
e^(t-y) = e^t . e^-y
OpenStudy (anonymous):
Oh duh forgot that property :)
OpenStudy (anonymous):
so separating them looks like this: e^y dy=te^t dt
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OpenStudy (anonymous):
then integrate both sides and you get e^y +\[c_{1}\]=te^t-e^t +\[c_{2}\]
OpenStudy (jamesj):
Or more simply,
\[ e^y = (t-1)e^x + C \]
thus y = ...
OpenStudy (anonymous):
combine c's and get e^y+\[c _{3}\]=te^t-e^t
OpenStudy (jamesj):
I mean (t-1)e^t + C
OpenStudy (jamesj):
\[ e^y = (t-1)e^t + C \]
thus y = ...
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OpenStudy (anonymous):
y=tln(t-1)+\[c _{4}\]
OpenStudy (jamesj):
No, you can't take the constant outside.
OpenStudy (jamesj):
ln(a + b) does not equal ln a + ln b
OpenStudy (jamesj):
hence
\[ y = \ln( (t-1)e^t + C) \]
OpenStudy (anonymous):
okay so it is y=ln(e^t(t-1)+\[c _{3}\])
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OpenStudy (anonymous):
and plugging in y(0)=5 gives me \[c _{3}\]=e^5 ???
OpenStudy (jamesj):
Indeed
OpenStudy (anonymous):
so the final answer would be: y=ln(e^t(t-1)+e^5)
OpenStudy (jamesj):
You can verify this by making sure it satisfies the original equation.
OpenStudy (anonymous):
opps \[c _{3}\]=e^5 +1
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OpenStudy (anonymous):
and it works :)
OpenStudy (jamesj):
good