$\frac{3mn^2}{m^{-4}n^{-2}}$

$\int19e^xsin\left(x\right)dx$

$\left(ab+5\right)\cdot\left(ab-6\right)$

$2^{0}\cdotx^{3}\cdot\sen\left(y\right)+\sqrt{xy}$

$\sin x\cdot\frac{\cot x}{\sec x}$

$\lim_{x\to0}\left(\frac{1}{3+2^{\frac{1}{x}}}\right)$

$\left(1-3a\right)\left(3ax+1\right)$