Find the Sixth Term in the Sequence 3n-3: Linear Expression Problem

Sequence Terms with Substitution Method

3n3 3n-3

What is the sixth term in the sequence?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:05 Let's find the sixth term.
00:09 Substitute the number six into the formula. Then, let's solve it together.
00:22 Remember, multiply and divide before adding and subtracting.
00:31 And that's how we solve it. Great job!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

3n3 3n-3

What is the sixth term in the sequence?

2

Step-by-step solution

The problem asks us to find the sixth term in the sequence defined by 3n33n - 3.

To solve this problem, we'll use the following steps:

  • Step 1: Identify the sequence formula, which is an=3n3a_n = 3n - 3.
  • Step 2: Determine which term we need, which is the sixth term, so n=6n = 6.
  • Step 3: Substitute n=6n = 6 into the formula.
  • Step 4: Calculate the result.

Now, let's work through these steps:

Step 1: We have the formula for the sequence as an=3n3a_n = 3n - 3.

Step 2: We need to find the sixth term, so n=6n = 6.

Step 3: Substitute n=6n = 6 into the formula:

a6=3(6)3a_6 = 3(6) - 3

Step 4: Perform the calculation:

a6=183=15a_6 = 18 - 3 = 15

Therefore, the sixth term in the sequence is 15.

3

Final Answer

15

Key Points to Remember

Essential concepts to master this topic
  • Formula: Use an=3n3 a_n = 3n - 3 where n is the term position
  • Technique: Substitute n = 6 into formula: 3(6)3=15 3(6) - 3 = 15
  • Check: Verify by calculating first few terms: 0, 3, 6, 9, 12, 15 ✓

Common Mistakes

Avoid these frequent errors
  • Using the formula value as the term number
    Don't think that 3n - 3 means the 3rd term minus 3 = wrong answer! This confuses the formula with position. Always substitute the position number (n = 6) into the entire expression 3n - 3.

Practice Quiz

Test your knowledge with interactive questions

Look at the following set of numbers and determine if there is any property, if so, what is it?

\( 94,96,98,100,102,104 \)

FAQ

Everything you need to know about this question

What does the 'n' represent in the formula?

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The n represents the position of the term in the sequence. So for the 6th term, n = 6, for the 10th term, n = 10, and so on.

How do I know which number to substitute for n?

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Look at what the question is asking! If it says "sixth term," then n = 6. If it says "tenth term," then n = 10. The term number equals the n value.

Why do we get 0 for the first term?

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When n = 1: 3(1)3=0 3(1) - 3 = 0 . This is correct! Some sequences start with 0, and that's perfectly normal in mathematics.

Can I just add 3 to each term to find the next one?

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Yes! This sequence increases by 3 each time (0, 3, 6, 9, 12, 15...). But using the formula 3n3 3n - 3 is more reliable, especially for terms far in the sequence.

What if I need to find a term like the 100th term?

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The formula method is perfect for this! Just substitute n = 100: 3(100)3=297 3(100) - 3 = 297 . Much easier than counting up 100 terms!

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