Final answer:
The correct permutation equation when x items must be together in an arrangement of y terms is option A, which is x! * (y - 1)!.
Step-by-step explanation:
The student is asking about a permutation equation where a certain number of items (x) must be positioned together in an arrangement that includes a total of y items. To solve this, we consider the x items that need to be together as a single unit. This single unit can be arranged within y items in (y - 1)! ways because we're effectively treating the x items as one. Within this single unit, the x items themselves can be arranged in x! ways. Therefore, the correct equation would be the product of the number of arrangements of the single unit in the larger set (y - 1)! and the number of arrangements within the unit x!, which matches option A: x! * (y - 1)!.