Evaluate 2(2n-2): Finding the Position of 20 in the Sequence

Given a formula with a constant property that depends onn n :

2(2n2) 2(2n-2)

Is the number 20 Is it part of the series? If so, what element is it in the series?

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Step-by-step video solution

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00:00 Is the number 20 a term in the sequence? And if so, what is its position?
00:03 Let's place the desired term in the sequence formula and solve
00:08 If the solution for N is positive and whole, the number is a term at position N in the sequence
00:13 Let's minimize as much as possible
00:22 Let's isolate N
00:39 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

Given a formula with a constant property that depends onn n :

2(2n2) 2(2n-2)

Is the number 20 Is it part of the series? If so, what element is it in the series?

2

Step-by-step solution

To determine if the number 20 is part of the sequence given by the formula 2(2n2)2(2n-2), we proceed as follows:

  • Step 1: Set up the equation, 2(2n2)=202(2n-2) = 20.
  • Step 2: Simplify the equation:
    2(2n2)=4n42(2n-2) = 4n - 4, thus we have 4n4=204n - 4 = 20.
  • Step 3: Solve for nn:
    Add 4 to both sides: 4n4+4=20+44n - 4 + 4 = 20 + 4 gives 4n=244n = 24.
    Divide both sides by 4: n=244=6n = \frac{24}{4} = 6.
  • Step 4: Check if nn is a positive integer.
    n=6n = 6 is indeed a positive integer.

Since n=6n = 6 is a positive integer, 20 is indeed part of the sequence, and it is the 6th term.

Therefore, the solution to the problem is Yes, 6.

3

Final Answer

Yes, 6 6

Practice Quiz

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Is there a term-to-term rule for the sequence below?

18 , 22 , 26 , 30

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