Let z=[y] and y=[x]-x, where [.] is the greatest integer function. If x is <strong>NOT</strong> an integer but positive, then what is the value of z ?

  1. A. -1
  2. B. 0
  3. C. 1
  4. D. 2

Correct Answer: A. -1

Explanation

Since x is not an integer, we can write x = n + f where n is an integer and 0 \lt f \lt 1. Then [x] = n. Substituting this into y, we get y = n - (n + f) = -f. Because 0 \lt f \lt 1, we have -1 \lt -f \lt 0, meaning -1 \lt y \lt 0. The greatest integer less than or equal to y is -1. Thus, z = [y] = -1.

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