$\left(4a-7b-9c-5d\right)^2$

$-\frac{286}{-11}$

$\frac{2\tan\left(x\right)}{1-\tan\left(x^2\right)}$

$\lim_{x\to\infty}\left(sqrt\left(x^2+5\cdot x-7\right)-sqrt\left(x^2+3\cdot x+1\right)\right)$

$\left(3h\:+\:2k\:-\:3m\right)\:\left(2k\:-\:3h\:+\:2m\right)$

$10x^2-20am$

$\frac{-6x^2y}{-12x^3y^4}$