\[bx^{2} + (2b - 1)x + b = 0,\]
\[b \neq 0\]
\[D = 4b^{2} - 4b + 1 - 4b^{2} =\]
\[= - 4b + 1 > 0\]
\[- 4b > - 1,\ \ b < \frac{1}{4},\]
\[b < 0,25\]
\[Ответ:( - \infty;0) \cup (0;0,25).\]