[tex]\frac{1}{x-1}-\frac{3}{x+2}=\frac{1}{4}\\
\\
\frac{x+2-3(x-1)}{(x-1)(x+2)}=\frac{1}{4}\\
\\
\frac{x+2-3x+3}{(x-1)(x+2)}=\frac{1}{4}\\
\\
\frac{5-2x}{x^2+x-2}=\frac{1}{4}\\
\\
4(5-2x)=x^2+x-2\\
\\
20-8x=x^2+x-2\\
\\
\boxed{x^2+9x-22=0}
[/tex]
Solvin this quadratic equation with Bhaskara formula we find:
x = -11 or x = 2