$\frac{45}{2}x-15y\cdot x^2+\frac{5}{2}y^2\cdot x^3$

$sec^2x=sin^2x$

$2\left(x\:-\:8\right)\:+\:3x$

$\frac{4}{5}x^2.\frac{3}{2}x$

$3\cdot\left(6-2\right)^2$

$\lim_{x\to\infty}\sqrt{x+\sqrt{x+\sqrt{x}}}-\sqrt{x}$

$\left(-\sqrt[3]{2\:+\:\left(-5\right)^2}\:+\:\sqrt{81}:\:\left(-3\right)\right)^2$