$y\:2\:-\:\:\:6y\:-\:72\:=\:$

$\left(\frac{x}{x+y}\right)\le1$

$6ab^2c^3+18a^2b^2c^2-12a^3b^4c$

$\int\frac{1}{1+sin\left(2x\right)}dx$

$5\:+\:\left\{\:8\:-\:\left[\:5\:-\:2\:+\:\left(2\:-\:3\right)\:+\:8\:-\:\left(-\:7\:-\:5\right)\right]\right\}$

$\frac{\left(x^2+8x-9\right)}{\left(x^2+3x-4\right)}$

$\lim_{x\to0}\frac{\sqrt{x+a+b}-\sqrt{a+b}}{x},a>0,b>0$