Multiple choice

What is the sum of first 10 terms of the given sequence? 18, 36, 54, ...

  1. 960

  2. 970

  3. 980

  4. 990
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D Correct answer
Explanation

This is an arithmetic progression with a=18, d=18, n=10. Sum = (n/2) * (2a + (n-1)d) = 5 * (36 + 9*18) = 5 * (36 + 162) = 5 * 198 = 990.

AI explanation

The given sequence is an arithmetic progression with the first term a = 18 and the common difference d = 18. The sum of the first n terms of an arithmetic progression is calculated using the formula S = n/2 multiplied by (2a + (n-1)d). Substituting the values gives S = 10/2 multiplied by (2 multiplied by 18 + 9 multiplied by 18), which equals 5 multiplied by (36 + 162). This results in 5 multiplied by 198, giving a sum of 990.

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