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

$\left(2m^3-7\right)\left(2m^3-5\right)$

$\frac{3x^4-7x^2+2x^3-x+1}{3x-1}$

$\frac{729+64a^3}{9+4a}$

$3ab^2+14ab-14a^2c-10ab+4a^2b+3a^2b$

$\lim_{x\to\infty}\left(\tan\left(\frac{\pi x}{2x+1}\right)\right)^{\frac{1}{x}}$

$\left(10\right)\cdot\left(20\right)-\left(10\right)\cdot\left(-40\right)$