$\lim_{k\to\infty}\left(\frac{\left(k+1\right)x}{3\left(k-1\right)}\right)$

$\left(n^2+2\right)\left(n^2-7\right)$

$\lim_{x\to1}\left(\frac{x^{9a}-9ax+9a-1}{\left(x-1\right)^2}\right)$

$2+-5\:\left(-4\right)$

$-\left\{50+\left[-70+\left(-10+30+40\right)-20\right]-8\right\}$

$\frac{d}{dx}\left(\frac{ln\sqrt{3x+2}}{x^3}\right)$

$x^5+x^4-x-x^6$