$\int\frac{5-4x}{x^2+4x-21}dx$

$2\:x-3\ge7$

$\left(4-\sqrt{8}\right)\left(\sqrt{8}+4\right)$

$\lim_{x\to0}\left(\frac{e^{2x}-1-20x}{400x^2}\right)$

$6\cos\left(7x\right)-3-6\cos\left(7x\right)\tan\left(x\right)+3\tan\left(x\right)=0$

$\left(\frac{7}{6}m^3y^4+9\right)\left(\frac{7}{6}m^3y^4-9\right)$

$x^2+12x+36=25$