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I am solving this system in mathematica

w = 0.1;
f3[a_, b_, x_] = w^2 x^5 + w (1 + a) x^4 + (a - b) x^3 - w;
f6[a_, b_, x_] = D[f3[a, b, x], x];
f7[a_, b_] := x /. NSolve[f6[a, b, x] == 0, x];
ContourPlot[f3[a, b, f7[a, b]][[1]] == 0, {a, -2, 0}, {b, -2, 0}]

I get Solve::ratnz error, but I do not see where the system is inexact.

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  • $\begingroup$ Try with w = 1/10 $\endgroup$ – user9660 Jan 28 '16 at 19:15
  • $\begingroup$ That worked! Can I ask why that mattered? $\endgroup$ – Gregory Jan 28 '16 at 19:18
  • $\begingroup$ @Louis Thanks for your help. $\endgroup$ – Gregory Jan 28 '16 at 19:36
  • $\begingroup$ See Exact and Approximate Results and read the helps with the very instructive tutorials. Have fun! $\endgroup$ – user9660 Jan 28 '16 at 19:36
  • $\begingroup$ Then you could answer your question itself, would be a brisk approach! $\endgroup$ – user9660 Jan 28 '16 at 19:38