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Let A be the sum of the first 20 terms and B be the sum of the first 40 terms of the series 1 2 + 2.2 2 + 3 2 + 2.4 2 + 5 2 + 2.6 2 + …. If B – 2A = 100 λ , then λ is equal to :

1. 232
2. 248
3. 464
4. 496

Correct answer: 248

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