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Prove the statement by using the Principle of Mathematical Induction: 2n < (n + 2)! for all natural number n. - Mathematics

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प्रश्न

Prove the statement by using the Principle of Mathematical Induction:

2n < (n + 2)! for all natural number n.

सिद्धांत

उत्तर

P(n) is 2n < (n + 2)!

So, substituting different values for n, we get,

P(0) ⇒ 0 < 2!

P(1) ⇒ 2 < 3!

P(2) ⇒ 4 < 4!

P(3) ⇒ 6 < 5!

Let P(k) = 2k < (k + 2)! is true;

Now, we get that,

⇒ P(k + 1) = 2(k + 1)((k + 1) + 2))!

We know that,

[(k + 1) + 2)! = (k + 3)! = (k + 3)(k + 2)(k + 1) ............. 3 × 2 × 1]

But, we also know that,

= 2(k + 1) × (k + 3)(k + 2) ............ 3 × 1 > 2(k + 1)

Therefore, 2(k + 1) < ((k + 1) + 2)!

⇒ P(k + 1) is true when P(k) is true.

Therefore, by Mathematical Induction,

P(n) = 2n < (n + 2)! Is true for all natural number n.

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पाठ 4: Principle of Mathematical Induction - Exercise [पृष्ठ ७१]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 11
पाठ 4 Principle of Mathematical Induction
Exercise | Q 12 | पृष्ठ ७१

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