(x²+x+1)+(x²-x+1)

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

First, let's simplify the terms within the parentheses separately:

x² + x + 1

x² - x + 1

Now, we will add the like terms together:

(x² + x + 1) + (x² - x + 1)

= x² + x² + x - x + 1 + 1

= 2x² + 2

Therefore, the simplified expression is 2x² + 2.