$\lim_{x\to0.2}\frac{\sin\left(x\right)}{1+\tan\left(x\right)}$

$\sin^2\left(x-90\right)+sin^2\left(-x\right)$

$93a^3b^2c-62a^2b^3c^2-124a^2b$

$454+230$

$\frac{dy}{dx}=\frac{x\sqrt{x^2+1}}{e^y}$

$x\frac{dy}{dx}=3x^2y^2+xy^2$

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