$\log\left(\frac{x\sqrt{x+1}}{x^2-1}\right)=\log\left(x\right)-\frac{1}{2}\log\left(x+1\right)-\log\:\left(x-1\right)$

$\frac{tan\:155^{\circ\:}-tan\:35^{\circ\:}}{1+tan\:155^{\circ\:}\:tan\:35^{\circ\:}}$

$\frac{d^2}{dx^2}\left(4x^2+y^2=52\right)$

$\cos^2a+\cos^2a\cdot\cot^2a$

$\frac{dy}{dx}=8xe^{5y}$

$5x^4b^4+25a^8b^3-30a^9b^4$

$\frac{12a^2+6ab-15a^2b^2}{-3a^2}$