GATE AG 2012 • Q63 MCQ • 2 Marks

Section 8: General Aptitude

Quantitative Aptitude

Subtopic: Numerical Computation

Question Statement:

If a prime number on division by 4 gives a remainder of 1, then that number can be expressed as:

Options:

  • (A) sum of squares of two natural numbers
  • (B) sum of cubes of two natural numbers
  • (C) sum of square roots of two natural numbers
  • (D) sum of cube roots of two natural numbers

Official Answer Key:

A

Step-by-Step Solution & Explanation

This is Fermat's theorem on sums of two squares: every prime p ≡ 1 (mod 4) can be written as the sum of two perfect squares (e.g., 5=1²+2², 13=2²+3²). Answer: A.

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