Re: How to prevent Solve from DSolve?
- To: mathgroup at christensen.cybernetics.net
- Subject: [mg910] Re: How to prevent Solve from DSolve?
- From: chen at fractal.eng.yale.edu (Richard Q. Chen)
- Date: Sun, 30 Apr 1995 03:44:36 -0400
- Organization: Yale University
Sorry I made a typing error in saying that the implicit solution to the ODE
DSolve[2 y[x] + (x + y[x]) y'[x] == 0, y[x], x]
is
f(x,y) = y*(y+2x)^2 = C[1]
It is actually
f(x,y) = y*(y+3x)^2 = C[1]
Verification:
In[1]:= Solve[D[y[x]*(y[x]+3x)^2,x]==0,y'[x]]
-2 y[x]
Out[1]= {{y'[x] -> --------}}
x + y[x]
In[2]:= 2 y[x] + (x + y[x]) y'[x] == 0/.%[[1]]
Out[2]= True
--
Richard Q. Chen
chen at fractal.eng.yale.edu