$\frac{\left(-3\right)^7}{\left(-3\right)^4}$

$\lim\:_{x\to\:2\:\:}\frac{x^2}{1-\sqrt{cosx}}$

$9^0\:\cdot\:9^0\:$

$cos\left(sin^{-2}\left(x\right)-tan^{-1}\left(y\right)\right)$

$4^2x\:4^4x\:4^4$

$180x^2-39x-\left(-25x^2\right)$

$\lim_{x\to\infty}\left(\frac{x^4+3x}{3x^3-4x^2}\right)$