$\frac{dv}{du}=-\frac{\left(5v-u\right)}{\left(3v-7u\right)}$

$\left(12x-19y-3\right)-\left(7x+15y+8\right)$

$\left(x+3\right)\left(-6x-7\right)$

$\lim_{x\to5}\left(\frac{x^3-9x^2+15x+25}{x^3+5x^2+2x-10}\right)$

$4x^2-8xy+16y$

$\lim_{x\to-\infty}\frac{\left(-2x\right)}{\left(x-\sqrt{\left(x^2+2x\right)}\right)}$

$\tan^2\left(x\right)=3\left(\sec\left(x\right)-1\right)$