$2\ln-\left(3\ln y-4\ln z\right)$

$\frac{d}{dx}x+xy+y=2$

$u^2-18u+81$

$\lim_{x\to\infty}\left(e^x\left(\arctan x-\frac{\pi}{2}\right)\right)$

$\frac{d}{dx}7y^2+5x=-2y-3x^2$

$\left(\cos\left(x\right)\right)^2-\left(\sin\left(x\right)\right)^2=\frac{5}{4}$

$\left(-\frac{1}{2}\right)-\frac{1}{2}$