Medium INTEGER +4 / -1 PYQ · JEE Mains 2021

Let A = {n $\in$ N | n2 $\le$ n + 10,000}, B = {3k + 1 | k$\in$ N} an dC = {2k | k$\in$N}, then the sum of all the elements of the set A $\cap$(B $-$ C) is equal to _____________.

Answer (integer) 832

Solution

B $-$ C $\equiv$ {7, 13, 19, ......, 97, .......}<br><br>Now, n<sup>2</sup> $-$ n $\le$ 100 $\times$ 100<br><br>$\Rightarrow$ n(n $-$ 1) $\le$ 100 $\times$ 100<br><br>$\Rightarrow$ A = {1, 2, ......., 100}.<br><br>So, A$\cap$(B $-$ C) = {7, 13, 19, ......., 97}<br><br>Hence, sum = ${{16} \over 2}(7 + 97) = 832$

About this question

Subject: Mathematics · Chapter: Sets, Relations and Functions · Topic: Sets and Operations

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