Polynomials

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Summation

    6 + 24 + 60 + 120 + 210 + 336 + 504 + 720…. upto 10 terms is equal to?
    1. 3680
    2. 4290
    3. 5720
    4. 6170

 

  • Correct Answer
    Choice B. 4290

Explanatory Answer

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Detailed Solution

= 1 × 2 × 3 + 2 × 3 × 4 + 3 × 4 × 5 + 4 × 5 × 6 + 5 × 6 × 7....
= n (n + 1) (n + 2)
Or, (m – 1) m (m + 1) where m = n + 1
= m3 – m
Sum of all these =
=
Substituting m = n + 1, we get . ….. Surprisingly enough, this seems to work!!!
Substituting n = 10,
We get .
= 10 × 11 × 3 × 13 = 4290
Answer choice (b)


Correct Answer: 4290.



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