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Let S = 2 + 7 6 + 2 7 12 + 3 7 20 + 4 7 30 + ..... Then 4S is equal to-

1. 2 3 7 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛
2. 2 3 3 7
3. 3 3 7 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛
4. 3 2 3 7

Correct answer: 3 3 7 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛

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