$\left(3a^2b-5ab^5\right)^2$

$3\:.\:\left(-4-3\right)+2\:.\:\left(8-12\right)-9\::\left(6-3\right)$

$81x^2+3x+36$

$-2\left(\:3k\:-\:5\right)\:+\:2\left(\:k\:+\:1\right)$

$\left(50-i\cdot1000\right)\left(50+i\cdot1000\right)$

$3\cdot y-8\cdot z+8^2$

$\left(m+2\right)\left(m-2\right)\left(m^2+7\right)$