(x²+x+1)+(x²-x+1)

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

Starting with the terms with x², we have x² + x², which equals 2x².

Next, we have x + (-x), which cancels out to 0.

Lastly, we have 1 + 1, which equals 2.

Putting it all together, we have 2x² + 2.