(x²+x+1)+(x²-x+1)

To simplify the given expression, we can combine like terms.

(x² + x + 1) + (x² - x + 1)

Simplifying within each set of parentheses first, we have: x² + x + 1 + x² - x + 1

Combining like terms, we can add the coefficients of similar terms: (1x² + 1x²) + (1x - 1x) + (1 + 1)

Simplifying further, we get: 2x² + 0x + 2

And since 0x is equal to 0, we can simplify it to: 2x² + 2

So, the simplified form of (x² + x + 1) + (x² - x + 1) is 2x² + 2.