$$12-\left(4-\left(13-7\right):3+2\right)-5$$

$$7\log\left(81.55\right)$$

$$16x^5y^4\left(14x^2y^2\right)$$

$$x^4=256$$

$$\lim_{x\to\infty}\left(\frac{\cos\left(\pi x\right)-1}{\sqrt{x}-2}\right)$$

$$x^2-27=0$$

$$\left(a^2b^3b\right)^4$$