44. A question is given followed by two Statements I and II. Consider the Question and the Statements and mark the correct option. Question: Is (p + q)² – 4pq, where p, q are natural numbers, positive? Statement I: p
q. Which one of the following is correct in respect of the above Question and the Statements?
- A. The Question can be answered by using one of the Statements alone, but cannot be answered using the other statement alone.
- B. The Question can be answered by using either Statement alone.
- C. The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone.
- D. The Question can be answered even without using any of the Statements.
Answer: B
Explanation
First, simplify the expression:
(p + q)² – 4pq = p² + 2pq + q² – 4pq = p² – 2pq + q² = (p – q)²
The question asks: Is (p – q)² positive?
A square of any real number is always non-negative (≥ 0). It is positive if and only if the base is not zero. So, (p – q)² is positive if p – q ≠ 0, which means p ≠ q.
Statement I: p < q.
If p q.
If p > q, then p ≠ q. Therefore, (p – q)² will be positive. This statement alone is sufficient.
Since either Statement I alone or Statement II alone is sufficient to answer the question, the correct option is (b). This question tests basic algebraic identities and properties of numbers, a common element in CSAT.