Find the Eighth Term in the n/2 Sequence Formula

Sequence Formulas with Term Position Substitution

What is the eighth element of the sequence below?

n2 \frac{n}{2}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the 8th element in the sequence
00:03 Let's substitute the position of the corresponding element in the sequence formula and solve
00:08 Let's substitute N = 8 in the sequence formula
00:15 And this is the solution to the problem

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

What is the eighth element of the sequence below?

n2 \frac{n}{2}

2

Step-by-step solution

To find the eighth element of the sequence defined by the formula n2 \frac{n}{2} , we will follow these steps:

  • Identify the formula provided for the sequence: an=n2 a_n = \frac{n}{2} .
  • Determine the position in the sequence we need: n=8 n = 8 .
  • Substitute n=8 n = 8 into the formula to find a8 a_8 .

Substituting n=8 n = 8 into the formula, we have:

a8=82 a_8 = \frac{8}{2} .

This simplifies to a8=4 a_8 = 4 .

Therefore, the eighth element of the sequence is 4 4 .

3

Final Answer

4

Key Points to Remember

Essential concepts to master this topic
  • Formula Rule: Substitute term position n directly into sequence formula
  • Technique: Replace n with 8 in n2 \frac{n}{2} to get 82=4 \frac{8}{2} = 4
  • Check: Verify that position 8 gives a8=4 a_8 = 4 by computing 82 \frac{8}{2}

Common Mistakes

Avoid these frequent errors
  • Using the formula value instead of position number
    Don't substitute the answer 4 back into the formula = circular reasoning! This doesn't tell you which term you found. Always substitute the position number (n = 8) into the given formula n2 \frac{n}{2} .

Practice Quiz

Test your knowledge with interactive questions

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

18 , 22 , 26 , 30

FAQ

Everything you need to know about this question

What does n represent in the sequence formula?

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The variable n represents the position of the term in the sequence. For the 1st term, n = 1; for the 8th term, n = 8. It's like the term's address in the sequence!

How do I know which number to substitute for n?

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Look at what the question is asking for! If it asks for the eighth element, then n = 8. If it asked for the 5th term, then n = 5. The position number always equals n.

Why isn't the answer 8 since we want the eighth term?

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The position is 8, but the value at that position is different! We substitute n = 8 into n2 \frac{n}{2} to get 82=4 \frac{8}{2} = 4 . Think of it like house addresses - house #8 might have 4 people living in it!

What would the first few terms of this sequence look like?

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Let's see:

  • 1st term (n=1): 12=0.5 \frac{1}{2} = 0.5
  • 2nd term (n=2): 22=1 \frac{2}{2} = 1
  • 3rd term (n=3): 32=1.5 \frac{3}{2} = 1.5
The sequence is: 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, ...

Can sequence formulas give decimal or fraction answers?

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Absolutely! Sequences can have any type of numbers - whole numbers, fractions, decimals, even negative numbers. The formula n2 \frac{n}{2} gives us fractions when n is odd and whole numbers when n is even.

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