$\frac{2x^2-x-1}{-x^2+2x-1}$

$\int_{-\pi}^{\pi}\left(-c\cdot\cos\left(x\right)\sin\left(x\right)\right)dx$

$\frac{-x^4-4x^3+6x^2-7}{x^2-2}$

$\int-\frac{2x}{\sqrt{1-4x^2}}dx$

$\frac{4\left(3v+5\right)\left(v-2\right)}{28\left(v-2\right)\left(2v+5\right)}$

$\int\left(yx+y\right)y^xdy$

$\sqrt{\frac{\:x}{a^2b\:}}-\sqrt{\frac{x}{ab^2}}$