$4m^2n^2\cdot3mn$

$12x^5y^4-16x^3y^4+28x^5$

$\lim_{x\to1}\left(\frac{2x^2+x-3}{x-1}\right)$

$\lim_{x\to\frac{\pi}{2}}\left(\frac{\ln\left(x-\frac{\pi}{2}\right)}{\sec\left(x\right)}\right)$

$\frac{16-b^4}{2-6}$

$\sin^3\left(x\right)+\cos^3\left(x\right)+\sin\left(x\right)\cos^2\left(x\right)+\sin\left(x\right)^2\cos\left(x\right)=\sin\left(x\right)+\cos\left(x\right)$

$y'=\frac{x^2}{y}$