In the drawing, four main structures of the series.
Choose the algebraic expression corresponding to the number of points in place of
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In the drawing, four main structures of the series.
Choose the algebraic expression corresponding to the number of points in place of
To solve this problem, we'll follow these steps:
Now, let's work through each step:
  
Step 1: Counting the points in each given structure, we observe that each subsequent structure increases the number of points in a linear fashion.
  
Step 2: By examining the counts, a pattern emerges where the number of points  relates to the number of structures . Specifically:
  
- When , suppose points are 1.
  
- When , suppose points are 5.
  
- When , suppose points are 9, and so forth.
  
The pattern follows an arithmetic progression with a constant increment of 4 points per subsequent structure step (from  to ), while starting from 1.  
Step 3: Based on this pattern, the number of points can be described by the expression . This formula accounts for the consistent increase (common difference) of 4, starting from yielding the first point count.
Therefore, the solution to the problem is .
Is there a term-to-term rule for the sequence below?
18 , 22 , 26 , 30
Look for a constant difference between consecutive terms. If the number of points increases by the same amount each time (like +4 in this problem), it's arithmetic!
Start by making a table: write n=1, 2, 3, 4 in one column and count the corresponding points in another. The pattern becomes much clearer this way!
Test each given option! Substitute n=1, n=2, n=3 into each formula and see which one matches your point counts from the diagram.
The sequence starts at 1 point (when n=1), not 4 points. The formula accounts for this starting offset while maintaining the +4 pattern.
Absolutely! This count-and-pattern approach works for triangular numbers, square arrangements, and many other geometric sequences. Just be systematic in your counting!
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