Chapter 13: Problem 1
Use the Principle of Mathematical Induction to show that the given statement is true for all natural numbers \(n\). $$ 2+4+6+\cdots+2 n=n(n+1) $$
Short Answer
Expert verified
By induction, the statement is true for all natural numbers n.
Step by step solution
01
- Base Case
Verify the statement for the initial value, typically when n=1. Substituting n=1 into the left-hand side, we get: $$2 = 2(1)$$. Substituting n=1 into the right-hand side, we get: $$1(1+1) = 2$$. Thus, the base case is true.
02
- Induction Hypothesis
Assume that the statement is true for some arbitrary natural number k. This means we assume that: $$2 + 4 + 6 + \cdots + 2k = k(k+1)$$
03
- Inductive Step
Now we need to show that the statement is true for k+1. Consider the sum for k+1 terms: $$2 + 4 + 6 + \cdots + 2k + 2(k+1)$$. Using the induction hypothesis, this can be written as: $$k(k+1) + 2(k+1)$$.
04
- Simplify
Simplify the expression obtained in the previous step: $$k(k+1) + 2(k+1) = (k+1)(k + 2)$$. This simplifies to: $$(k+1)((k+1) + 1).$$
05
- Conclusion
Since we have shown that if the statement is true for n=k, then it is also true for n=k+1, by the principle of mathematical induction, the statement is true for all natural numbers n.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
base case
The Base Case is the first critical step of a mathematical induction proof. It's used to show that the given statement holds true for the initial value of the natural number, commonly starting with n=1.
In our exercise, the given series is:
\[2 + 4 + 6 + \rightarrow + 2n = n(n+1)\rightarrow \]
For the base case, we substitute n=1 into both sides of the equation:
In our exercise, the given series is:
\[2 + 4 + 6 + \rightarrow + 2n = n(n+1)\rightarrow \]
For the base case, we substitute n=1 into both sides of the equation:
- Left-hand side: \[2\]
- Right-hand side: \[1(1+1) = 2\]
induction hypothesis
The Induction Hypothesis is the second stage in a mathematical induction proof. Here, you assume the statement to be true for some arbitrary natural number, k. This assumption helps in creating a standard setting for the next step.
In our case, we assume that the statement holds true for n=k, which implies:
In our case, we assume that the statement holds true for n=k, which implies:
- \[2 + 4 + 6 + \rightarrow + 2k = k(k + 1)\]
inductive step
The Inductive Step is the core of mathematical induction, where we show that if the statement holds true for an arbitrary number k, it also holds for k+1. To do this, we need to incorporate our assumption from the induction hypothesis:
Consider the sum for k+1 terms:
This demonstrates that our statement is true for k+1, based on the assumption that it was true for k.
Consider the sum for k+1 terms:
- \[2 + 4 + 6 + \rightarrow + 2k + 2(k+1)\]
- \[k(k+1) + 2(k+1)\]
- \[k(k+1) + 2(k+1) = (k+1)(k+2)\]
This demonstrates that our statement is true for k+1, based on the assumption that it was true for k.
sum of series
The concept of the Sum of Series plays a vital role in this problem. Here, we're dealing with an arithmetic series whose terms increase by a common difference. The series given is:
By using the principle of mathematical induction, we effectively validate this formula holds for all natural numbers n.
- \[2 + 4 + 6 + \rightarrow + 2n\]
- \[n(n + 1)\]
By using the principle of mathematical induction, we effectively validate this formula holds for all natural numbers n.