$25b^2d^2-10bd^2+1$

$\lim_{x\to4}\left(\frac{64-x^3}{32-2x^2}\right)$

$\frac{1}{25}2^8+\frac{25}{36}b^6-\frac{1}{3}a^4b^3$

$2-1+4$

$\lim_{x\to\frac{\pi}{2}}\left(\frac{1-sin\left(x\right)}{1+cos\left(x\right)}\right)$

$\left(2x^3+y\right)^3$

$\left(3c-y\right)\left(y+3c\right)$