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Prove by the principle of mathematical induction: 32n + 7 is divisible by 8 for all n ϵ N |
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Answer» Suppose P (n): 32n + 7 is divisible by 8 Now let us check for n = 1, P (1): 32 + 7 = 9 + 7 = 16 P (n) is true for n = 1. Where, P (n) is divisible by 8 Then, let us check for P (n) is true for n = k, and have to prove that P (k + 1) is true. P (k): 32k + 7 is divisible by 8 : 32k + 7 = 8λ : 32k = 8λ – 7 … (i) Now we have to prove, 32(k + 1) + 7 is divisible by 8 32k + 2 + 7 = 8μ Therefore, = 32(k + 1) + 7 = 32k.32 + 7 = 9.32k + 7 = 9.(8λ – 7) + 7 by using equation (i) = 72λ – 63 + 7 = 72λ – 56 = 8(9λ – 7) = 8μ P (n) is true for n = k + 1 Thus, P (n) is true for all n ∈ N. |
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