(x²+x+1)+(x²-x+1)

To add these two polynomials, we can simply combine like terms.

First, let's combine the terms with the same degree:

(x² + x²) + (x - x) + (1 + 1)

Simplifying further, we have:

2x² + 2

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