PolynomialMod[(x-2)(3x^2/7 + 2x/7) + (x^2 + x + 1)k, (x^2 + x + 1)], k =1

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.