$\left(\:-\:72\:+\:24\:-\:48\:-\:12\:\right)\::\:\left(\:+\:12\:\right)\:$

$5\sqrt{6}-10\sqrt{6}$

$( 6 x ^ { 2 } y ^ { 4 } ) ( - 3 x ^ { 4 } y ^ { 4 } )$

$\left(\frac{7x+9}{3x-5}\right)\left(\frac{\sqrt{x-10}}{x}\right)$

$25\::\:\left(1\right)\::\:\left(-25\right)$

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

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