Final answer:
The term that must be added to x² + 7x to complete the square is 12.25, resulting in the perfect square trinomial (x + 3.5)².
Step-by-step explanation:
To complete the square for the quadratic expression x² + 7x, you would add the square of half the coefficient of x. The coefficient of x is 7, so half of this is 3.5. Squaring 3.5 gives us 12.25.
Therefore, the term that must be added to x² + 7x to complete the square is 12.25. Once added, the expression x² + 7x + 12.25 can be rewritten as the perfect square trinomial (x + 3.5)².