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TS EAMCET · Maths · Application of Derivatives

A variable straight-line \(L\) with negative slope passes through the point \((4,9)\) and cuts the positive coordinate axes in A and B. If O is the origin, then the minimum value of \(\mathrm{OA}+\mathrm{OB}\) is

  1. A \(25\)
  2. B \(12\)
  3. C \(13\)
  4. D \(5\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(25\)

Step-by-step Solution

Detailed explanation

Let the line be \(\frac{x}{a} + \frac{y}{b} = 1\). It passes through \((4,9)\): \(\frac{4}{a} + \frac{9}{b} = 1\). We want to minimize \(\mathrm{OA} + \mathrm{OB} = a+b\). \(a+b = (a+b)\left(\frac{4}{a} + \frac{9}{b}\right)\)…