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Saturday, 31 October

JEE Main 2021 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 4 August 2021, Shift 2, Maths Q64

Question 64 of 90 in this shift, Maths question 4 of 30, Section A.

If CrC_r (r=0,1,2,…,11r=0,1,2,\ldots,11) are the Binomial coefficients in the expansion of (1+x)11(1+x)^{11}, then the value of C0+(C0+C1)+(C0+C1+C2)+…..+(C0+C1+….+C11)C_0+(C_0+C_1)+(C_0+C_1+C_2)+\ldots..+(C_0+C_1+\ldots.+C_{11}) is
  1. (1)13.21013.2^{10}Official answer
  2. (2)13.21113.2^{11}
  3. (3)23.21023.2^{10}
  4. (4)23.21123.2^{11}

Official answer

Option 1

NTA final key.

Same idea in other shifts

Asked 2× in all
  1. 26 Jul 2022, Shift 2 · Q4∑i,j=0i≠jnnCi nCj\sum_{\substack{i,j=0\\ i\neq j}}^{n}{}^nC_i\,{}^nC_j is equal toMediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.