Prove (6" -1) is ÷ by 5, Vne N 1. Show true for n =1 6' -1=5 2. Assume true for n = k 6* -1 is ÷ by 5

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Chapter1: Functions And Models
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Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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### Mathematical Induction Proof 

**Objective:**
Prove that \(6^n -1\) is divisible by 5 for all natural numbers \(n\).

**Step 1: Base Case**
Show true for \(n = 1\):
\[ 6^1 - 1 = 5 \]
Since 5 is clearly divisible by 5, the base case holds true.

**Step 2: Inductive Hypothesis**
Assume the statement is true for \(n = k\). That is, assume:
\[ 6^k - 1 \text{ is divisible by } 5 \]
or equivalently,
\[ 6^k - 1 = 5m \]
for some integer \(m\).

**Step 3: Inductive Step**
We need to show the statement is true for \(n = k + 1\). That is, we need to prove:
\[ 6^{k+1} - 1 \text{ is divisible by } 5 \]

Starting with the left hand side:
\[ 6^{k+1} - 1 \]
Rewrite \(6^{k+1}\) as \(6 \cdot 6^k\):
\[ 6 \cdot 6^k - 1 \]

Now, use the inductive hypothesis:
\[ 6 \cdot (5m + 1) - 1 \]

Distribute 6 in the brackets:
\[ 6 \cdot 5m + 6 \cdot 1 - 1 = 30m + 6 - 1 = 30m + 5 \]

Factor 5 out of the expression:
\[ 5(6m + 1) \]

Since the result is \(5\) multiplied by an integer \((6m + 1)\), it is divisible by \(5\).

**Step 4: Conclusion**
By the principle of mathematical induction, \(6^n - 1\) is divisible by 5 for all natural numbers \(n\).
Transcribed Image Text:### Mathematical Induction Proof **Objective:** Prove that \(6^n -1\) is divisible by 5 for all natural numbers \(n\). **Step 1: Base Case** Show true for \(n = 1\): \[ 6^1 - 1 = 5 \] Since 5 is clearly divisible by 5, the base case holds true. **Step 2: Inductive Hypothesis** Assume the statement is true for \(n = k\). That is, assume: \[ 6^k - 1 \text{ is divisible by } 5 \] or equivalently, \[ 6^k - 1 = 5m \] for some integer \(m\). **Step 3: Inductive Step** We need to show the statement is true for \(n = k + 1\). That is, we need to prove: \[ 6^{k+1} - 1 \text{ is divisible by } 5 \] Starting with the left hand side: \[ 6^{k+1} - 1 \] Rewrite \(6^{k+1}\) as \(6 \cdot 6^k\): \[ 6 \cdot 6^k - 1 \] Now, use the inductive hypothesis: \[ 6 \cdot (5m + 1) - 1 \] Distribute 6 in the brackets: \[ 6 \cdot 5m + 6 \cdot 1 - 1 = 30m + 6 - 1 = 30m + 5 \] Factor 5 out of the expression: \[ 5(6m + 1) \] Since the result is \(5\) multiplied by an integer \((6m + 1)\), it is divisible by \(5\). **Step 4: Conclusion** By the principle of mathematical induction, \(6^n - 1\) is divisible by 5 for all natural numbers \(n\).
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