$$-\:9\:-\:\left(-4\:\right)\:-\:\left(\:+12\:\right)\:$$

$$4x^2-8=0$$

$$\int x^2\sqrt{x^3+36}dx$$

$$\left(3^4\cdot3^3\right)^2$$

$$\tan\left(20\right)\left(65+s\right)$$

$$\int\left(a^2-x^2\right)^{-\frac{1}{2}}\:dx$$