Final answer:
To make the expression x² + x a perfect-square trinomial, you need to add 1/4.
Step-by-step explanation:
To make the expression x² + x a perfect-square trinomial, you need to add the square of half the coefficient of the x term. In this case, the coefficient of x is 1, so half of it is 1/2. The square of 1/2 is 1/4. Therefore, you need to add 1/4 to the expression to make it a perfect-square trinomial.
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