UPSC CSE Prelims 2026
The correct option is (a) - Select this option if the question can be answered using one of these statements alone, but cannot be answered using other statement.
[as per provisional answerkey]Statement I alone:
We are given that x, y, and z are integers greater than 1. Let's find the prime factorization of 116:
.
Since the equation is and y must be an integer greater than 1, the only possible value for is (which is 4).
If , then (which is > 1).
Substituting this back: , which gives .
Since 29 is a prime number, we get a definitive "Yes" to the question "Is x a prime number?".
Statement I alone is sufficient.
Statement II alone:
We are given , where x and z are integers greater than 1. Let's find the factors of 261:
.
Possible pairs for (x, z) such that both are greater than 1 are:
1. , (x is prime)
2. , (x is NOT prime)
3. , (x is prime)
4. , (x is NOT prime)
Because x can be either prime (3, 29) or composite (9, 87), we cannot determine if x is definitely a prime number.
Statement II alone is not sufficient.
Prime factorization and integer constraints (x, y > 1) in algebraic equations to determine unique values.