divide.x^4+x^2-80/x+3

Answer 1

-3|1 0 1 0 -80
...... -3 9-30 90
.....1-3 10-30 10

the above is to show the algorithm of synthetic division. It is hard to show a nice matrix in this forum
my answer represents x^3 - 3x^2 + 10x - 30 with a remainder of 10

the following page shows how to do it using long algebraic division

Answer 2

forgot to post the webpage

http://www.sosmath.com/algebra/factor/fac01/fac01.html