Decoding the Pattern: Determine the Term-to-Term Rule of 13, 16, 19, 22

Arithmetic Sequences with Nth Term Formula

What is the term-to-term rule of the following sequence?

13, 16, 19, 22

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the sequence formula
00:04 Identify the first term according to the given data
00:11 Note the constant difference between terms
00:17 This is the constant difference
00:21 Use the formula to describe an arithmetic sequence
00:26 Substitute appropriate values and solve to find the sequence formula
00:38 Properly expand brackets, multiply by each factor
00:47 Continue solving
00:57 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

What is the term-to-term rule of the following sequence?

13, 16, 19, 22

2

Step-by-step solution

To solve this problem, the sequence 13, 16, 19, 22 must be analyzed to find the term-to-term rule.

Step 1: Identify the common difference.

Subtract the first term from the second term:
1613=3 16 - 13 = 3

Verify the difference throughout the sequence:
1916=3 19 - 16 = 3
2219=3 22 - 19 = 3

The common difference d d is 3 3 .

Step 2: Use the arithmetic sequence formula.

Start with the general formula for an arithmetic sequence:
an=a1+(n1)d a_n = a_1 + (n-1) \cdot d

In this sequence, a1=13 a_1 = 13 and d=3 d = 3 . Substitute these values in:
an=13+(n1)3 a_n = 13 + (n-1) \cdot 3

Simplify the expression:

an=13+3n3 a_n = 13 + 3n - 3

an=3n+10 a_n = 3n + 10

The term-to-term rule of the sequence is 3n+10 3n + 10 .

Examining the given choices, the correct choice is:

3n+10 3n + 10 (Choice 2).

3

Final Answer

3n+10 3n+10

Key Points to Remember

Essential concepts to master this topic
  • Common Difference: Subtract consecutive terms to find constant difference
  • Formula: Use an=a1+(n1)d a_n = a_1 + (n-1)d where a1=13 a_1 = 13 and d=3 d = 3
  • Check: Verify 3n+10 3n + 10 gives 13, 16, 19, 22 for n = 1, 2, 3, 4 ✓

Common Mistakes

Avoid these frequent errors
  • Using the wrong formula or confusing term-to-term vs nth term
    Don't write the common difference as the rule = just gives +3! This only tells how to get the next term, not the formula for any term. Always use the nth term formula an=a1+(n1)d a_n = a_1 + (n-1)d to find the general rule.

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's the difference between term-to-term rule and nth term formula?

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The term-to-term rule tells you how to get from one term to the next (like +3). The nth term formula lets you find any term directly without calculating all the previous ones!

How do I know if I found the right common difference?

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Check that the difference is the same between every pair of consecutive terms. In this sequence: 16-13=3, 19-16=3, 22-19=3. All equal 3, so d=3 is correct!

Why does the formula become 3n + 10 instead of staying as 13 + (n-1)×3?

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Both forms are correct! We expand 13+(n1)×3 13 + (n-1) \times 3 to get 13+3n3=3n+10 13 + 3n - 3 = 3n + 10 . The simplified form is easier to use.

Can I check my answer by plugging in different values of n?

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Absolutely! Test your formula: For n=1: 3(1)+10=13 ✓, n=2: 3(2)+10=16 ✓. If all match the original sequence, your formula is correct!

What if the sequence doesn't have a constant difference?

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Then it's not an arithmetic sequence! Check for other patterns like multiplying by a constant (geometric) or look for quadratic patterns if differences of differences are constant.

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