Multiple choice

Find the sum of the first $8$ terms of an arithmetic sequence whose first three terms are as follows : $7,10.5, 14,.....$

  1. 143.5

  2. 154

  3. 162.5

  4. 168

  5. 176.5
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B Correct answer
Explanation

a = 7, d = 3.5. Sum = n/2 * (2a + (n-1)d) = 8/2 * (14 + 7 * 3.5) = 4 * (14 + 24.5) = 4 * 38.5 = 154.

AI explanation

The arithmetic sequence has a first term of 7 and a common difference of 3.5. Using the formula for the sum of n terms, S = n/2 times (2a + (n-1)d), the sum of the first 8 terms is 8/2 times (14 + 7 times 3.5). This evaluates to 4 times 38.5, which equals 154.

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