Q58 / 90 · JEE Main 2016 (09 Apr Online) · Mathematics

For x ∈R, x≠-1, if 1+x2016+x1+x2015+x21+x2014+…+x2016= ∑ i=0 2016 a i x i , then a17 is equal to

  • Correct answer
    A
    2017!17!2000!
  • B
    2016!17!1999!
  • C
    2016!16!
  • D
    2017!2000!

Solution

S=1+x2016+x1+x2015+x21+x2014+……+x20151+x+x2016  ...i

x1+x S=x 1+x2015+x21+x2014+…+x2016+x20171+x  ...ii

ii-i

S1+x=1+x2016-x20171+x

∴ S=1+x2017-x2017

Coefficient a17=2017C17 =2017!17!2000!

Hence, the correct answer is option: 'A'.

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