Non linear second order diff eq

rbetzel
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I'm trying to find a substitution that works for the nonlin diffeq

y''+a(y')^2-by=0

Any suggestions?
 
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If you differentiate again, you get

y^{'''} + 2ay^{'} \cdot y^{''} - b = 0 right?

If you let

u = y^{'} you get u^{''} + 2a u^{'}u - b = 0
 
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