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

If $\alpha$, $\beta$ are natural numbers such that
100$\alpha$ $-$ 199$\beta$ = (100)(100) + (99)(101) + (98)(102) + ...... + (1)(199), then the slope of the line passing through ($\alpha$, $\beta$) and origin is :

  1. A 540
  2. B 550 Correct answer
  3. C 530
  4. D 510

Solution

RHS = $\sum\limits_{r = 0}^{99} {(100 - r)(100 + r)}$<br><br>$= {(100)^3} - {{99 \times 100 \times 199} \over 6} = {(100)^3} - (1650)199$<br><br>LHS = (100)<sup>$\alpha$</sup> $-$ (199)<sup>$\beta$</sup><br><br>So, $\alpha$ = 3, $\beta$ = 1650<br><br>Slope = tan$\theta$ = ${\beta \over \alpha }$<br><br>$\Rightarrow$ tan$\theta$ = 550

About this question

Subject: Mathematics · Chapter: Sequences and Series · Topic: Arithmetic Progression

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