$\left(1+\sin\left(a\right)\right)\left(1-\sin\left(a\right)\right)=\frac{1}{\sec\left(a\right)}$

$\left(8m^2n^2\right)\cdot\left(9a^2mx^2\right)$

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

$\frac{dy}{dx}=\frac{7y^2}{x}$

$-1^{\frac{1}{3}}$

$\sin\left(x\right)\left(cscx+cosx\right)+cscx\left(senx+secx\right)$

$-15x^6-5x^5+10x^4+20x^3$