$21\frac{1}{4}x^2-2$

$16m^2\left(a+b\right)^2-40m\left(a+c\right)+25$

$4x^6yz+14xy^2-21xy$

$\left(1100-135\right)+\left(680-75\right)+\left(800-120\right)-267$

$200+6+8+12-2$

$\frac{log_b\left(k\right)}{log_b\left(9\right)}$

$\frac{dy}{dx}=\frac{e^{-y^2}}{y}\left(x-1\right)$