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JEE Advanced · Mathematics · 25. AOD

The maximum value of the function \(f(x)=2 x^3-15 x^2+36 x-48\) on the set \(A=\left\{x \mid x^2+20 \leq 9 x\right\}\) is

  1. A 5
  2. B 10
  3. C 9
  4. D 11
Verified Solution

Answer & Solution

Correct Answer

(A) 5

Step-by-step Solution

Detailed explanation

Given, \(\quad A=\left\{x \mid x^2+20 \leq 9 x\right\}\) \(=\{x \mid x \in[4,5]\}\)
Now, \(f^{\prime}(x)=6\left(x^2-5 x+6\right)\)
Put \(\quad f^{\prime}(x)=0 \Rightarrow x=2,3\)
\(f(2)=-20, f(3)=-21\),
\(f(4)=-16, f(5)=7\)


From graph, maximum of \(f(x)\) on set \(A\) is \(f(5)=7\).
From JEE Advanced
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