(x²+x+1)+(x²-x+1)

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

Starting with the first term, x²+x+1, there are no other terms with x², so it remains the same.

Moving on to the second term, x²-x+1, there are no other terms with x, so it remains the same.

Finally, we add the constants, 1+1=2.

Therefore, the simplified expression is:

x² + x + 1 + x² - x + 1

Combining like terms, we get:

2x² + 2

So the simplified expression is 2x² + 2.