Question 86

Logical Reasoning Reasoning Analogies Medium

Let \(x, y\), and \(z\) be distinct integers. \(x\) and \(y\) are odd and positive and \(z\) is even and positive. Which one of the following statements cannot be true?

(A) \((x-z)^{2} y\) is even
(B) \((x-z) y^{2}\) is odd
(C) \((x-z) y\) is odd
(D) \((x-y)^{2} z\) is even
View Dynamic Solution & Explanation
Correct Solution: Option A

Step-by-step Solution:

Quick Solution

This problem tests the properties of odd and even numbers. The strategy is to determine the nature (odd or even) of the expressions in each statement based on the given conditions.


1. Establish the Basic Properties

From the problem statement, we know:

  • x and y are ODD.
  • z is EVEN.

Using these facts, we can determine the nature of the core components found in the options:

  • The expression (x - z) evaluates to (ODD - EVEN), which is always ODD.
  • The expression (x - y) evaluates to (ODD - ODD), which is always EVEN.

2. Evaluate Each Statement

Now we can check each statement to see which one is impossible.

  • A. (x - z)²y is even
    • We know (x - z) is ODD, so (x - z)² is (ODD × ODD) = ODD.
    • We know y is ODD
    • Therefore, the full expression (x - z)²y = (ODD × ODD) = ODD.
    • The result is always ODD. The statement that it is "even" is a contradiction, so this statement cannot be true.
  • B. (x - z)y² is odd
    • (x - z) is ODD and y³ is (ODD × ODD) = ODD.
    • (ODD × ODD) = ODD. This statement is always true.
  • C. (x - z)y is odd
    • (x - z) is ODD and y is ODD. (ODD × ODD) = ODD. This statement is always true.
  • D. (x - y)²z is even
    • (x - y) is EVEN, so (x - y)² is EVEN. z is EVEN.
    • (EVEN × EVEN) = EVEN. This statement is always true.

Final Answer: The only statement that is impossible and can never be true is A. (x - z)²y² is even.