Question

Factor x^4+x^3-15x^2-9

Answer 1

you might notice that x^4 term menas that there are four zeroes, and that -9 has \[\pm 1, \pm 9 and \pm 3\] as its factors. Do you know synthetic divison or long division?

Answer 2

yes I do.

Answer 3

Sorry about the long wait.
then you'll have to take one of the factors, such as -9,
and so synthetic division with it. If it has no remainder, bingo! if not, move on to the next factor,