$-168,7+204,513+346-254187$

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

$\frac{1024\:\left(a\right)^6-726\left(b\right)^6}{4\left(a\right)+6\left(b\right)}$

$-0.695\cdot4^2+2.78\cdot4-17.03$

$0.8a^2+9a-1.3a^2-4a$

$\frac{x^2}{x^2+2}$

$\lim_{x\to1.1}\left(\frac{2x^2-x-1}{x-1}\right)$