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Q4 (CISF/2021) Science & Technology › Basic Science (Physics, Chemistry, Biology)

What is the value of the following sum ? 1 × 2 + 2×22+3×23+4×24+ ....... + 10x210

Result
Your answer: —  ·  Correct: A

Explanation

This is an Arithmetico-Geometric Progression (AGP) of the form S = Σ n·rn. The given series is S = 1·21 + 2·22 + 3·23 + ... + 10·210.

To solve, multiply the sum by the common ratio (r = 2):
2S = 1·22 + 2·23 + 3·24 + ... + 9·21

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