$x^2-x+4<0$

$6xy=x^4+3$

$\lim_{x\to-1}\left(\frac{x^2}{\left|x\right|}\right)$

$\lim_{x\to0}\left(\frac{\left(x^2-36\right)\left(x-6\right)}{x^2-12x+36}\right)$

$\frac{x}{5x+5}=\frac{1}{x+2}+\frac{1}{x^2+3x+2}$

$\left(\frac{4}{3}x-5\right):\left(-2\right)\ge\left(\frac{1}{2}x-1\right)$

$\left(3xy-2ab\right)\left(3xy+2ab\right)$