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Saturday, 31 October

JEE Main 2020 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 2 September 2020, Shift 2, Maths Q51

Question 51 of 75 in this shift, Maths question 1 of 25.

Let f:R→Rf : \mathbf{R} \to \mathbf{R} be a function which satisfies f(x+y)=f(x)+f(y) ∀ x,y∈Rf(x+y)=f(x)+f(y)\ \forall\ x,y \in \mathbf{R}. If f(1)=2f(1)=2 and g(n)=∑k=1(n−1)f(k)g(n)=\sum_{k=1}^{(n-1)} f(k), n∈Nn \in \mathbf{N} then the value of n, for which g(n)=20g(n)=20, is :
  1. (1)44
  2. (2)55Official answer
  3. (3)99
  4. (4)2020

Official answer

Option 2

NTA final key (Sep 2020).

Chapter
Relations and Functions
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.