$cos\left(\frac{4}{5}\right)cos\left(-\frac{12}{13}\right)-sin\left(-\frac{3}{5}\right)sin\left(\frac{5}{13}\right)$

$\frac{dy}{dx}=\frac{y}{x}\left(\ln\left(y\right)-\ln\left(x\right)\right)$

$\left(a+x^2\right)-\left(x+2\right)^2$

$m^3+m^2n+mn^2$

$\sin^{2}x+4\cos x+11$

$\frac{169x^4y^5-81x^2y^4}{13x^2y^3-9xy^2}$

$\cos\left(u\right)=-\cos\left(2u\right)$