$f\left(x\right)=\frac{x^2}{x^4+16}$

$\left(115x+35\right)\left(85x+22\right)-15x+14$

$4x^2\left(x^2\:-\:y^2\right)\:$

$\frac{-\infty^2+4\cdot\infty-4}{\infty^2-4\cdot\infty+3}$

$-16x^2y+12xy^2+10x^2y-2xy^2$

$5\left(2c-3\right)=3\left(3c-5\right)$

$\sin\left(x+30\right)=0.5$