$3\cos^2x+\cos x-4$

$13a+20b-19+18b-26a$

$\int_1^{\infty}\left(\frac{3}{e^x+5}\right)dx$

$\frac{x^2}{x^3-x}$

$\int\frac{2x^2+3x-1}{\left(x-2\right)\left(x^2+x+4\right)}dx$

$\frac{d}{dx}\left(\frac{\left(x-1\right)^{\frac{1}{2}}\left(4x+1\right)^{\frac{1}{4}}}{\left(x^5+3\right)^{\frac{1}{5}}}\right)$

$\frac{3}{1}\cdot\frac{x^2}{2}$