$xyz\:+\:xyz\:-\:xyz$

$\lim_{x\to\:4}\:-\frac{\left(2x-4\right)}{\left(x-4\right)^2}$

$9x^4-4x^2$

$\left[15-\left(2^3-\frac{10}{2}\right)\right]\cdot\left[5+\left(3\cdot2-4\right)\right]-3+\left(8-2\cdot3\right)$

$\int_0^1a^{3x}dx$

$2x^2+2\sqrt{2x}+1$

$x^2-2x+4\ge0$