(x²+x+1)+(x²-x+1)

To add the two expressions (x²+x+1) and (x²-x+1), we combine like terms.

The terms with x² do not have any like terms in the other expression, so we simply add them together: x² + x² = 2x²

Next, the terms with x have a positive x in the first expression and a negative x in the second expression. Therefore, we subtract the x term in the second expression from the x term in the first expression: x - (-x) = x + x = 2x

Lastly, the constant terms in both expressions are 1, so we add them together: 1 + 1 = 2

Combining all the terms, we have 2x² + 2x + 2 as the result of adding (x²+x+1) and (x²-x+1).