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72n – 32n is divisible by 4. |
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Answer» Let P(n): 7n – 3n is divisible by 4. For n = 1, P(1): 71 – 31 = 4 which is divisible by 4. ∴ P(1) is true. Let us assume P(k) is true for some k∈N i.e., 72n – 32n is divisible by 4. Thus, P(k) ⇒ P(k +1). Hence, by mathematical induction P(n) is true for all n∈N |
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