$x\:\frac{dy}{dx}+xy\:=1-y\:\:,\:\:y\left(1\right)=0$

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

$3x^{3}+5xy^{2}-25x$

$\frac{4x^2-20x+5}{4}$

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

$\lim_{x\to0}\left(\cos\left(x\right)\left(e^{x^2}\right)\right)^{\frac{4}{x^4}}\:$

$3.x^2+12$