(x²+x+1)+(x²-x+1)

To simplify the expression, we first need to combine like terms:

(x² + x + 1) + (x² - x + 1)

Combine the x² terms: x² + x² = 2x²

Combine the x terms: x - x = 0

Combine the constant terms: 1 + 1 = 2

Putting it all together, the simplified expression is:

2x² + 2