$\left(\left(2a\right)^2+6b\right)^2$

$4x+6=2x+8$

$\left(12-y\right).\frac{3}{2}-18+\frac{3y^2}{4y}$

$\left(-9\right)\left(-4\right)+\left(-4\right)\left(5\right)$

$\lim_{x\to0}\left(\frac{2\sin\left(8x^6\right)}{-3x}\right)$

$\frac{1}{2}m^2n+\frac{1}{3}m^2n+\frac{1}{4}m^2n+\frac{1}{6}m^2n$

$9x^2-42x+49=0$