The value of - C 1 15 + 2 · C 2 15 - 3 · 15 C 3 + . . . . . - 15 · C 15 15 + C 1 14 + C 3 14…

The value of -C115+2·C215-3·15C3+.....-15·C1515+C114+C314+C514+....+C1114 is equal to
  1. 214
  2. 213-13
  3. 216-1
  4. 213-14

Solution

-C115+2·C215-3·C315+-15·C1515+C114+C314++C1114

=r=115-1r·r·15Cr+C114+C314++C1114+C1314-C1314

=r=115-1r·15·Cr-114+213-14

=15-C014+C114..-C1414+213-14

=213-14

Asked in: JEE Main 2021 (24 Feb Shift 1)

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