$729^2-289^2$

$\sin2x=5\sin x$

$\lim_{x\to0}\left(\frac{sin\left(x\right)}{x^5}\right)$

$u+4=4$

$-2x^2-5x+2$

$\left(\frac{3}{7}x^2r^5\right)\left(-\frac{7}{3}x^3p^4q\right)\left(\frac{2}{5}xr^6p^3\right)$

$\lim_{x\to0}\left(\frac{x}{x^2+\:3.7487736x\:+\:801.682596}\right)$