$4\left(x+2\right)-20\left(x-6\right)$

$\left(10mn^2+13y^3\right)\left(10mn^2-13y^3\right)$

$\frac{\left|-1\right|+\left|-9\right|+\left|+2\right|}{\left|-1\right|+\left|-2\right|}$

$-3x^2+4x-3\ge0$

$45m^4-20m^4$

$\sec^2x\cdot\left(1-\csc^2\left(x\right)\right)=-\csc^2\left(x\right)$

$-6x^2+4lx-2l^2$