(x²+x+1)+(x²-x+1)

To add these two expressions together, we can simply combine like terms:

(x² + x + 1) + (x² - x + 1) = x² + x² + x - x + 1 + 1 = 2x² + 2

Therefore, the sum of (x² + x + 1) and (x² - x + 1) is 2x² + 2.