$\left(6a^2b^3+4\right)\left(6a^2b^3-6\right)$

$2y^2-2y-1$

$f\left(x\right)=8x^4-7x^2+5x$

$\frac{d^2y}{dx^2}\left(y=\left(x+3\right)^9\right)$

$2\:.\:\left(-8\right)\::\:\left(-4\right)$

$\left(2d-6y\right)^2$

$\left(\frac{3}{5}m+\frac{1}{2}\right)\left(\frac{3}{5}-\frac{1}{2}\right)$