$\left(\frac{1}{3}x^2-\frac{2}{5}y^3\right)\left(\frac{1}{3}x^2+\frac{2}{5}y^3\right)$

$x^2+6x=13$

$\left(9xy^2z^3-\frac{2}{3}y^4\right)^2$

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

$\frac{d^3}{dx^3}\left(\ln\left(x^2+1\right)\right)$

$a^3-a^2-3a+2$

$\left(-6a+11\right)+\left(2a-5\right)$