Submitted by Meryjoy99 on Tue, 05/16/2017 - 20:26

After differentiating the given expression and equating gradients I get four equations for a, b and n, which don't make sense altogether. Should I try to modify in some way the fraction of the D.E.?

Submitted by Meryjoy99 on Tue, 05/16/2017 - 20:26

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After differentiating the given expression and equating gradients I get four equations for a, b and n, which don't make sense altogether. Should I try to modify in some way the fraction of the D.E.?

## What are your four equations?

What are your four equations? Something you might have missed (that will make your life easier) is when you are comparing$$\frac{\alpha (a,b,n)x+\beta (a,b,n)y}{\gamma (a,b,n)x+ \delta (a,b,n)y} \text{ with } \frac{Ax+By}{Cx+Dy}, $$ you should include an arbitrary constant, say $k$, when equating coefficients so that the equations you get are of the form $$\alpha (a,b,n)=kA, \quad \beta (a,b,n)=kB, \quad \gamma (a,b,n)=kC,\quad \delta (a,b,n)=kD.$$