using long division what is x^(7)-9x^(6)+19x^(5)+23x^(4)-108x^(3)+82x^2)+64x-120 divided by (x+3)
For this one, long division is quite impractical.
Use synthetic division,
Here is a page that explains it quite nicely.
http://mathcentral.uregina.ca/QQ/database/QQ.09.06/h/edward1.html