hi, i have three math factor proves i can't figure out:(adsbygoogle = window.adsbygoogle || []).push({});

1. Show that x-y is a factor of x^n-y^n

Through empircal testing, i figured out the other factor must be x^(n-1) + x^(n-2)y + x^(n-3)y^2 + ... + y^(n-1), though i can't come up with a prove for it..

2. Prove that (x+a) is a factor of (x+a)^5 + (x+c)^5 + (a-c)^5

3. prove that (x-a) is a factor of x^3 - (a+b+c)x^2 + (ab+bc+ca)x - abc

the last two i have no idea where to begin.. Can someone please help me? thanks :D

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Some questions about math factor proves

**Physics Forums | Science Articles, Homework Help, Discussion**