$\frac{12x+21}{16x^2-49}$

$\cos\left(x-\frac{\pi}{8}\right)=\frac{1}{\sqrt{2}}$

$\frac{d^3}{dx^3}\left(x\cdot\cos\left(x\right)\right)4x^2-6x+2$

$4\left(x^3+y^3\right)dx=3\left(xy^2\right)dy$

$\frac{2}{x}=\frac{x+1}{5}$

$\int\left(x^{-4}y\right)dx$

$\left(xy+2x^2y\right)^2$