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MATHEMATICAL CONNECTIONS Use inductive reasoning to write a formula for the sum of the first n positive even integers.

The sum is _.​

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User Nenchev
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The first even number is 2. So, the sum of the first 1 even number is 2.

The first two even numbers are 2 and 4. So, the sum of the first 2 even numbers is 2 + 4 = 6.

The first three even numbers are 2, 4, and 6. So, the sum of the first 3 even numbers is 2 + 4 + 6 = 12.

The first four even numbers are 2, 4, 6, and 8. So, the sum of the first 4 even numbers is 2 + 4 + 6 + 8 = 20.

From these observations, we can notice a pattern:

For n = 1, the sum is 2.

For n = 2, the sum is 6.

For n = 3, the sum is 12.

For n = 4, the sum is 20.

It appears that the sum of the first n even numbers can be represented as a function of n. Let's denote this sum as ∑n. Using inductive reasoning, we can derive a formula based on the pattern we've observed:

∑n = 2 + 4 + 6 + ... + (2n)

To find a formula, we can factor out the common term of 2:

∑n = 2(1 + 2 + 3 + ... + n)

Now, we need to find a formula for the sum of the first n positive integers, which is a well-known arithmetic series formula:

Sum of the first n positive integers = n(n + 1))/2

So, substituting this into our equation:

∑n = 2*(n(n + 1)/2)

Now, simplify:

∑n = n(n + 1)

Therefore, the formula for the sum of the first n positive even integers using inductive reasoning is:

∑n = n(n + 1)

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User Casper Beyer
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