Final answer:
To make the expression x² + x a perfect-square trinomial, the value that must be added is 1/4.
Step-by-step explanation:
To make the expression x² + x a perfect-square trinomial, we need to find the value that, when added to it, results in a perfect square.
A perfect-square trinomial is of the form (x + a)², where a is the value we are looking for.
In this case, to make x² + x a perfect-square trinomial, we can rewrite it as (x + 1/2)² = x² + x + 1/4. So, the value that needs to be added is 1/4.
Learn more about perfect-square trinomial