Identify the Hidden Properties: Analyze the Number Sequence 1, 3, 9, 26, 81

Sequence Pattern Analysis with Missing Properties

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

1,3,9,26,81 1,3,9,26,81

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Is there any pattern? And if so, what is it?
00:03 Let's observe the change between terms
00:09 The change here is not equal, therefore there is no pattern
00:24 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

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

1,3,9,26,81 1,3,9,26,81

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Check if the sequence is an arithmetic sequence.
  • Step 2: Check if the sequence is a geometric sequence.
  • Step 3: Explore other patterns if neither arithmetic nor geometric sequence fits.

Now, let's work through each step:

Step 1: Checking for arithmetic sequence:
To be an arithmetic sequence, the difference between consecutive terms should be constant.
For 1,3,9,26,811, 3, 9, 26, 81:
31=23 - 1 = 2
93=69 - 3 = 6
269=1726 - 9 = 17
8126=5581 - 26 = 55
The differences are not the same, so it is not an arithmetic sequence.

Step 2: Checking for geometric sequence:
To be a geometric sequence, the ratio of consecutive terms should be constant.
For 1,3,9,26,811, 3, 9, 26, 81:
31=3\frac{3}{1} = 3
93=3\frac{9}{3} = 3
269\frac{26}{9} is not 3, similarly 8126\frac{81}{26} is not constant.
Thus, it is not a geometric sequence either.

Step 3: Explore other non-trivial patterns:
Without straightforward arithmetic or geometric patterns identified, try other patterns or sequences, but given the options provided, none of the numerical patterns visibly connect through such standard sequences. This suggests examining deeper provides diminishing returns without knowing additional context or rules that these numbers follow.

Evaluating choices: None of the options directly covers a standard pattern or rule fitting all these points consistently, indicating no obvious, identical property unifies the set.

Therefore, the correct answer is Does not exist, as there isn't an evident mathematical property or pattern connecting these numbers uniformly.

3

Final Answer

Does not exist

Key Points to Remember

Essential concepts to master this topic
  • Testing Rules: Check arithmetic differences and geometric ratios systematically
  • Technique: Calculate 31=2,93=6,269=17 3-1=2, 9-3=6, 26-9=17 for differences
  • Check: No constant difference or ratio means no simple pattern exists ✓

Common Mistakes

Avoid these frequent errors
  • Assuming every sequence must have a pattern
    Don't force a pattern when differences like 2, 6, 17, 55 show no consistency = wrong conclusion! This leads to inventing fake patterns that don't actually exist. Always accept that some sequences have no discernible mathematical property.

Practice Quiz

Test your knowledge with interactive questions

12 ☐ 10 ☐ 8 7 6 5 4 3 2 1

Which numbers are missing from the sequence so that the sequence has a term-to-term rule?

FAQ

Everything you need to know about this question

How do I know if a sequence has no pattern?

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After checking arithmetic differences and geometric ratios, if neither shows consistency, the sequence likely has no simple pattern. Not every set of numbers follows a mathematical rule!

What if I see a pattern in just some of the numbers?

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A true sequence pattern must work for all consecutive terms. If it only works for 2-3 numbers but breaks down elsewhere, it's not a valid pattern for the entire sequence.

Should I try more complex patterns like squares or cubes?

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You can explore patterns like n2,n3 n^2, n^3 , but given the answer choices, focus on basic arithmetic and geometric patterns first. Complex patterns are rarely the answer in introductory problems.

Why is 'Does not exist' even an option?

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Mathematics teaches us to be honest about our findings. If no clear pattern emerges after systematic checking, the correct mathematical conclusion is that no pattern exists.

Could there be a pattern I'm missing?

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While advanced patterns exist, this question tests your ability to systematically check basic patterns and recognize when they don't apply. Trust your systematic analysis!

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