$2r+3s-5r$

$\left(-5x^3+4x^2-2x\right)+\left(2x^4+3x^2+8x-7\right)$

$\int\left(\frac{6x}{\left(7+x^2\right)^3}\right)dx$

$\lim_{x\to0}\left(\frac{e^2-\left(1-x\right)}{x}\right)$

$11x-6w-4z\:de\:19z-1w+3x$

$\frac{d}{dx}\left(x^x\right)ln\left(x^2+1\right)$

$\log8\left(x+2\right)^2=2$