$$\left. \begin{array} { l } { \quad ( a ) ( a - 1 ) x ^ { 2 } - ( a + 1 ) x + ( a + 1 ) \gt 0 \text { Y e \right.$$
$\left\{\begin{matrix}a\in \left(-\infty,-\frac{\sqrt{x^{4}+6x^{3}-5x^{2}-2x+1}-x^{2}-x+1}{2x^{2}}\right)\cup \left(\frac{\sqrt{x^{4}+6x^{3}-5x^{2}-2x+1}+x^{2}+x-1}{2x^{2}},\infty\right)\text{, }&x\neq 0\\a\neq \frac{x^{2}+x-1}{2x^{2}}\text{, }&x\neq 0\text{ and }x^{4}+6x^{3}-5x^{2}-2x+1\leq 0\\a\in \mathrm{R}\text{, }&x^{4}+6x^{3}-5x^{2}-2x+1<0\text{ and }x\neq 0\end{matrix}\right.$
