Multiple choice

What is the 26th term of the sequence 1.5, 4.5, 9.5, 16.5,...?

  1. 476.5

  2. 576.5

  3. 676.5

  4. 776.5
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C Correct answer
Explanation

Differences: 3, 5, 7. This is an arithmetic progression of differences. The n-th term is a_n = a_1 + sum(2k+1). The sequence follows n^2 + 0.5. For n=26, 26^2 + 0.5 = 676 + 0.5 = 676.5.

AI explanation

The sequence follows the pattern of the term's position squared plus half of one, giving the formula n^2 plus 0.5. For the 26th term, calculate 26 squared plus 0.5. Since 26 squared is 676, adding 0.5 gives 676.5.

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