$f\left(x\right)=\frac{x-1}{x^{2}-x}$

$-12\:-\:7\:+\:\left[\:-\:4\:\left(\:-\:2\:-\:3\:\right)\:+\:5\:-\:\left(\:-\:10\:-\:2\right)\right]\:+\:15$

$e^{\left(\frac{1}{x-2}\right)\cdot\ln\left(\frac{x}{2}\right)}$

$\sqrt{13^2}-12^2$

$\frac{d^2}{dy^2}\left(log\left(x-y\right)\right)$

$x^5+4x^4-12x^3-34x^2+11x+30$

$-4b^2+80b$