$\left(5a^2b^3\right)\left(6a^3b\right)$

$\left(x^2-2x-3\right)\cdot\left(2x^3-5x^2-4x+3\right)$

$\frac{\sin x}{cscx}+\frac{\cos x}{\sec x}$

$\left(4mn+6\right)\left(7mn-9\right)$

$8u^7-28u^6+20u^5$

$\frac{dy}{dx}\left(xy+x^2y^2=5\right)$

$\lim_{h\to0}\left(\frac{2-2cos\left(h\right)-sin^2\left(h\right)}{h}\right)$