$\left(3x-5y\right)\cdot\left(3x+5y\right)$

$\int9t\:cos\left(t\right)dt$

$cos\left(x+\frac{\pi}{6}\right)+sin\left(x-\frac{\pi}{3}\right)$

$8xy+4i-8yx-3i$

$\left(\frac{1}{4}x^2y+10\right)\left(2xy^2-xy\right)\left(8xy^2+\frac{2}{5}\right)$

$e^{2y}-y\cos\left(xy\right)dx+\left(2e^{2y}-x\cos\left(xy\right)+2y\right)dy=0$

$\lim_{x\to\infty}\left(\frac{\tan\left(x\right)}{\frac{21}{2x-\pi}}\right)$