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Use mathematical induction to show:5n + 9 ≤ 6n, for all integers n ≥2.

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Answer:

We will prove the statement by mathematical induction.

Base case: For n=2, we have 5(2) + 9 = 19 and 6(2) = 12. Clearly, 19 ≤ 12 is false, so the base case does not satisfy the inequality.

Inductive step: Assume that for some integer k ≥ 2, 5k + 9 ≤ 6k holds. We will show that 5(k+1) + 9 ≤ 6(k+1) also holds.

Starting with the left-hand side of the inequality:

5(k+1) + 9 = 5k + 5 + 9 = 5k + 14

Since k ≥ 2, we can use the inductive hypothesis to write:

5k + 9 ≤ 6k

Adding 5 to both sides:

5k + 14 ≤ 6k + 5

Substituting back into the left-hand side of the original inequality:

5(k+1) + 9 ≤ 6k + 5 = 6(k+1)

Therefore, we have shown that if the statement holds for some integer k ≥ 2, then it also holds for k+1.

Conclusion: By the principle of mathematical induction, the statement 5n + 9 ≤ 6n holds for all integers n ≥ 2.

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