$a^2x^6-b^2y^4$

$\left(16x-7y\right)^2$

$\left(2a^8-5a^4\right)^2$

$\lim_{x,y\to0,1}\left(\frac{y}{x}\right)$

$\frac{dy}{dx}=2\left(\sec\left(x\right)\right)^2\left(y+3\right)$

$\frac{\sin\left(x\right)^4-\sin\left(x\right)^6}{cos\left(x\right)^4-\cos\left(x\right)^6}$

$=\frac{x^{2}-3}{x^{2}+2}$