$\left(x^2+2\sqrt{x}\right)\left(x^2-2\sqrt{x}\right)$

$x^2+5x-14$

$\left(\left(2x-3y\right)-4\right)^2$

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

$\left(\frac{3}{4}w^5+5m^3\right)\left(\frac{3}{4}w^5-5m^3\right)$

$-4x+2y+2y+z-3x+2y-2z$

$-15\left(2\right)^2$