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📐 Mathematics  ·  Principle of Mathematical Induction  ·  JEE

Using induction to prove the sum of squares formula n(n+1)(2n+1)/6, what is P(2)?

Answer: 1 + 4 = 2(3)(5)/6.

  • A 1 + 4 = 2(3)(5)/6
  • B 1 + 4 = 10
  • C 5 = 5
  • D 1 + 2 = 5

Correct answer: A. 1 + 4 = 2(3)(5)/6

Explanation: P(2) states 1<sup>2</sup> + 2<sup>2</sup> = 2(3)(5)/6. Left side = 1+4 = 5, right side = 30/6 = 5. Both equal 5, confirming P(2) is true.

Induction as a Domino ChainP(1): base case fallsP(k) knocks down P(k+1)...and so on, foreverBase case = first domino tipped; inductive step = each domino guaranteed to tip the next one

Mathematical induction works like a row of dominoes: proving the base case P(1) tips the first domino, and proving the inductive step (P(k) ⟹ P(k+1)) guarantees each domino knocks over the next - together these two facts guarantee ALL dominoes fall, without checking each one individually.

Concept context

A proof technique used to establish that a statement is true for every natural number, using a base case and an inductive step.

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