(x²+x+1)+(x²-x+1)

To simplify the expression (x²+x+1)+(x²-x+1), we need to combine like terms.

In the first set of parentheses, we have x²+x+1. In the second set of parentheses, we have x²-x+1.

Combining the x² terms, we have x² + x² = 2x².

Combining the x terms, we have x - x = 0, so the x term cancels out.

Combining the constant terms, we have 1 + 1 = 2.

Therefore, the simplified expression is 2x² + 2.